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/* run.config OPT: -wp-no-print -wp-rte */ /* run.config_qualif OPT: -then -wp-rte -wp */ /* ************/ /* Solution de TP donné par Julien à L'IFIPS */ /* ************/ /* Questions: 1. Informellement, que calcule cette fonction? 2. Donner une spécification en ACSL de cette fonction. 3. Prouver cette fonction avec WP et Alt-Ergo. La preuve doit inclure la terminaison et l'absence d'erreur à l'exécution. */ /*@ requires len > 0; @ requires \valid(a+(0..len-1)); @ ensures 0 <= \result < len; @ ensures \forall integer i; 0 <= i < len ==> a[i] <= a[\result]; @ assigns \nothing; */ int exo1(int *a, int len) { int i = 0, j = len - 1; /*@ loop invariant 0 <= i <= j < len; @ loop invariant @ \forall integer k; @ (0 <= k < i || j < k < len) @ ==> (a[k] <= a[i] || a[k] <= a[j]); @ loop assigns i, j; @ loop variant j - i; */ while (i < j) if (a[i] <= a[j]) i++; else j--; return i; }
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typedef enum { Max, Min } kind; int extremum (kind k, int x, int y) { return ((k == Max ? x > y : x < y) ? x: y); } /*@ requires k == Max || k == Min; assigns \nothing; ensures \result == x || \result == y; behavior is_max: assumes k == Max; ensures \result >= x && \result >= y; behavior is_min: assumes k == Min; ensures \result <= x && \result <= y; complete behaviors is_max, is_min; disjoint behaviors is_max, is_min; complete behaviors; disjoint behaviors; */ int extremum (kind k, int x, int y);
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#include <limits.h> #include <string.h> /*@ logic integer cypher(int x0) = (((x0==26)) ? (0) : ((x0+1)));*/ /*@ requires ((0<=x0) && (x0<=26)); assigns \nothing; ensures ((0<=\result) && (\result<=26)); ensures \result == cypher(x0); */ int cypher(int x0) { int x2 = x0 == 26; int x4; if (x2) { x4 = 0; } else { int x3 = x0 + 1; x4 = x3; } return x4; } /*@ logic integer decypher(int x11) = (((x11==0)) ? (26) : ((x11-1)));*/ /*@ requires ((0<=x11) && (x11<=26)); assigns \nothing; ensures ((0<=\result) && (\result<=26)); ensures \result == decypher(x11); */ int decypher(int x11) { int x13 = x11 == 0; int x15; if (x13) { x15 = 26; } else { int x14 = x11 - 1; x15 = x14; } return x15; } /*@ requires ((((((x25>0) && \valid(x22+(0..x25-1))) && \valid(x23+(0..x25-1))) && \valid(x24+(0..x25-1))) && (\forall int x88; (((0<=x88) && (x88<x25)) ==> (\forall int x92; (((0<=x92) && (x92<x25)) ==> (\forall int x96; (((0<=x96) && (x96<x25)) ==> ((\separated(x22+x88,x23+x92) && \separated(x22+x88,x24+x96)) && \separated(x23+x92,x24+x96))))))))) && (\forall int x114; (((0<=x114) && (x114<x25)) ==> ((0<=x22[x114]) && (x22[x114]<=26))))); ensures ((((\forall int x126; (((0<=x126) && (x126<x25)) ==> (x23[x126]==cypher(x22[x126])))) && (\forall int x137; (((0<=x137) && (x137<x25)) ==> ((0<=x23[x137]) && (x23[x137]<=26))))) && (\forall int x149; (((0<=x149) && (x149<x25)) ==> (\old(x22[x149])==x22[x149])))) && (\forall int x159; (((0<=x159) && (x159<x25)) ==> (\old(x24[x159])==x24[x159])))); assigns x23[(0..x25-1)]; */ void encode(int * x22, int * x23, int * x24, int x25) { /*@ loop invariant 0<=x28<=x25; loop invariant (\forall int x29; (((0<=x29) && (x29<x25)) ==> ((0<=x22[x29]) && (x22[x29]<=26)))); loop invariant (\forall int x39; (((0<=x39) && (x39<x25)) ==> (\at(x22[x39],Pre)==x22[x39]))); loop invariant (\forall int x48; (((0<=x48) && (x48<x25)) ==> (\at(x24[x48],Pre)==x24[x48]))); loop invariant (\forall int x57; (((0<=x57) && (x57<x28)) ==> (x23[x57]==cypher(x22[x57])))); loop assigns x28, x23[(0..x25-1)]; loop variant x25-x28; */ for(int x28=0; x28 < x25; x28++) { int x71 = x22[x28]; int x72 = cypher(x71); x23[x28] = x72; /*@assert (x23[x28]==x72);*/ } } /*@ requires ((((((x172>0) && \valid(x169+(0..x172-1))) && \valid(x170+(0..x172-1))) && \valid(x171+(0..x172-1))) && (\forall int x235; (((0<=x235) && (x235<x172)) ==> (\forall int x239; (((0<=x239) && (x239<x172)) ==> (\forall int x243; (((0<=x243) && (x243<x172)) ==> ((\separated(x169+x235,x170+x239) && \separated(x169+x235,x171+x243)) && \separated(x170+x239,x171+x243))))))))) && (\forall int x261; (((0<=x261) && (x261<x172)) ==> ((0<=x169[x261]) && (x169[x261]<=26))))); ensures ((((\forall int x273; (((0<=x273) && (x273<x172)) ==> (x170[x273]==decypher(x169[x273])))) && (\forall int x284; (((0<=x284) && (x284<x172)) ==> ((0<=x170[x284]) && (x170[x284]<=26))))) && (\forall int x296; (((0<=x296) && (x296<x172)) ==> (\old(x169[x296])==x169[x296])))) && (\forall int x306; (((0<=x306) && (x306<x172)) ==> (\old(x171[x306])==x171[x306])))); assigns x170[(0..x172-1)]; */ void decode(int * x169, int * x170, int * x171, int x172) { /*@ loop invariant 0<=x175<=x172; loop invariant (\forall int x176; (((0<=x176) && (x176<x172)) ==> ((0<=x169[x176]) && (x169[x176]<=26)))); loop invariant (\forall int x186; (((0<=x186) && (x186<x172)) ==> (\at(x169[x186],Pre)==x169[x186]))); loop invariant (\forall int x195; (((0<=x195) && (x195<x172)) ==> (\at(x171[x195],Pre)==x171[x195]))); loop invariant (\forall int x204; (((0<=x204) && (x204<x175)) ==> (x170[x204]==decypher(x169[x204])))); loop assigns x175, x170[(0..x172-1)]; loop variant x172-x175; */ for(int x175=0; x175 < x172; x175++) { int x218 = x169[x175]; int x219 = decypher(x218); x170[x175] = x219; /*@assert (x170[x175]==x219);*/ } } /*@ requires ((((((x319>0) && \valid(x316+(0..x319-1))) && \valid(x317+(0..x319-1))) && \valid(x318+(0..x319-1))) && (\forall int x332; (((0<=x332) && (x332<x319)) ==> (\forall int x336; (((0<=x336) && (x336<x319)) ==> (\forall int x340; (((0<=x340) && (x340<x319)) ==> ((\separated(x316+x332,x317+x336) && \separated(x316+x332,x318+x340)) && \separated(x317+x336,x318+x340))))))))) && (\forall int x359; (((0<=x359) && (x359<x319)) ==> ((0<=x316[x359]) && (x316[x359]<=26))))); ensures ((\forall int x371; (((0<=x371) && (x371<x319)) ==> (x318[x371]==x316[x371]))) && (\forall int x381; (((0<=x381) && (x381<x319)) ==> (\old(x316[x381])==x316[x381])))); assigns x317[(0..x319-1)], x318[(0..x319-1)]; */ void autoencode(int * x316, int * x317, int * x318, int x319) { encode(x316,x317,x318,x319); decode(x317,x318,x316,x319); }
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#include "string.h" /*@ requires valid_string(s); assigns s[0..(strlen(s) - 2)]; ensures strlen(s) ≡ \old(strlen(s)); ensures s ≡ \old(s); */ void a(char* s); /*@ requires valid_string(s); assigns s[0..strlen(\old(s))]; ensures strlen(s) ≡ strlen(s); ensures s ≡ \old(s); */ void b(char *s) { int x = 0; a(s); //@ assert x ≡ 0; } /*@ requires valid_string(s); assigns s[0..n]; */ void an(char* s, int n); /*@ requires valid_string(s); assigns s[0..n]; */ void bn(char *s, int n) { an(s, n); }
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/*@ assigns \nothing; ensures \result == \max(\max(a, b), \max(b, c)); */ int max3(int a, int b, int c) { return a > b ? (a > c ? a : c) : (b > c ? b : c); }
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#include <stdio.h> #include <string.h> #include <limits.h> /*@ requires N >= 0 && \valid_read(a + (0..N-1)); assigns \nothing; behavior empty: assumes N == 0; ensures \result == 0; behavior not_empty: assumes 0 < N; ensures 0 <= \result < N; ensures \forall integer i; 0 <= i < N ==> a[i] <= a[\result]; ensures \forall integer i; 0 <= i < \result ==> a[i] < a[\result]; complete behaviors; disjoint behaviors; */ int max(int* a, int N) { if (N == 0) { return 0; } int i; int max = 0; /*@ loop invariant 0 <= i <= N; loop invariant 0 <= max < N; loop invariant \forall integer k; 0 <= k < i ==> a[k] <= a[max]; loop invariant \forall integer k; 0 <= k < max ==> a[k] < a[max]; loop assigns max, i; loop variant N-i; */ for (i = 0; i < N; i++) { if (a[max] < a[i]) { max = i; } } return max; } int main() { int N = 6; //int* a; //a = (int*) malloc(N*sizeof(int)); int a[N]; memcpy(a, (int[]) {23, 50, 61, 124, 562, 1000}, sizeof a); //a = {23, 50, 61, 124, 562, 1000}; //*(a + 0) = 23; //*(a + 1) = 50; //*(a + 2) = 61; //a[3] = 124; //a[4] = 563; //a[5] = 1000; // max from odd numbers int max_index = max(a, N); printf("max_from_arr = %i\n", a[max_index]); return 0; }
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// Command: frama-c -wp -wp-rte program.c // Frama-c version : Silicon (last release) // The algorithm is proved to sort, but does not ensure the preservation of the elements of the initial array // swap and same_elements are from http://nikolai.kosmatov.free.fr/publications/tutorial_2013_06_18_tap2013_slides.pdf /*@ predicate swap{L1, L2}(int *a, int *b, integer begin, integer i, integer j, integer end) = begin <= i < j < end && \at(a[i], L1) == \at(b[j], L2) && \at(a[j], L1) == \at(b[i], L2) && \forall integer k; begin <= k < end && k != i && k != j ==> \at(a[k], L1) == \at(b[k], L2); predicate same_array{L1,L2}(int *a, int *b, integer begin, integer end) = \forall integer k; begin <= k < end ==> \at(a[k],L1) == \at(b[k],L2); inductive same_elements{L1, L2}(int *a, int *b, integer begin, integer end) { case refl{L1, L2}: \forall int *a, int *b, integer begin, end; same_array{L1,L2}(a, b, begin, end) ==> same_elements{L1, L2}(a, b, begin, end); case swap{L1, L2}: \forall int *a, int *b, integer begin, i, j, end; swap{L1, L2}(a, b, begin, i, j, end) ==> same_elements{L1, L2}(a, b, begin, end); case trans{L1, L2, L3}: \forall int* a, int *b, int *c, integer begin, end; same_elements{L1, L2}(a, b, begin, end) ==> same_elements{L2, L3}(b, c, begin, end) ==> same_elements{L1, L3}(a, c, begin, end); } */ /*@ ghost int *t;*/ /*@ requires \valid(t+(0..n-1)); requires \separated(t+(0..n-1),a+(0..n-1)); requires same_array{Pre, Pre}(a, t, 0, n); requires n >= 0; requires \valid(a+(0..n-1)); assigns a[0..n-1],t[0..n-1]; ensures sorted: \forall integer i, j; 0 <= i <= j < n ==> a[i] <= a[j]; // the final array is sorted ensures \forall integer k; 0 <= k < n ==> a[k] == t[k]; ensures same_elements{Pre, Post}(t, t, 0, n); ensures same_elements{Pre, Post}(a, a, 0, n); // the array contains the same elements at the end as in the beginning */ void pair_sort(int a[], int n) { int i = 0; // i is running index (inc by 2 every iteration) /*@ loop invariant \forall integer k, l; 0 <= k <= l < i ==> a[k] <= a[l]; // the sub-array a[0..i-1] is sorted loop invariant same_elements{Pre, Here}(t, t, 0, n); loop invariant \forall integer k; 0 <= k < n ==> a[k] == t[k]; loop invariant 0 <= i <= n; loop assigns i, a[0..n-1],t[0..n-1]; loop variant n - 1 - i; */ while (i < n-1) { int x = a[i]; // let x and y hold the next to elements in A int y = a[i+1]; if (x < y) { // ensure that x is not smaller than y int tmp = x; x = y; y = tmp; } int j = i - 1; // j is the index used to find the insertion point /*@ loop invariant \forall integer k, l; 0 <= k <= l <= j ==> a[k] <= a[l]; // the sub-array a[0..j] is sorted loop invariant \forall integer k, l; j+2 < k <= l <= i+1 ==> a[k] <= a[l]; // the sub-array a[j+3..i+1] is sorted loop invariant \forall integer k, l; 0 <= k <= j && j +2 < l <= i+1 ==> a[k] <= a[l]; // every element in a[0..j] is no more then every element in a[j+3..i+1] loop invariant \forall integer k; j+2 < k <= i+1 ==> x < a[k]; // every element in a[j+3..i+1] is more than x loop invariant -1 <= j <= i - 1; loop invariant same_elements{Pre, Here}(t, t, 0, n); loop invariant \forall integer k; j+2 < k <= i+1 ==> a[k] == t[k]; loop invariant \forall integer k; i+1 < k < n ==> a[k] == t[k]; loop invariant \forall integer k; 0 <= k <= j ==> a[k] == t[k]; loop invariant (t[j+1] == x && t[j+2] == y) || (t[j+1] == y && t[j+2] == x); loop assigns a[0..n-1],j,t[0..n-1]; loop variant j; */ while (j >= 0 && a[j] > x) { // find the insertion point for x /*@ ghost L1:;*/ a[j+2] = a[j]; // shift existing content by 2 /*@ ghost int temp = t[j];*/ /*@ ghost t[j] = t[j+2];*/ /*@ ghost t[j+2] = temp;*/ /*@ assert swap{L1, Here}(t, t, 0, j, j+2, n);*/ j = j - 1; } /*@ ghost Test:;*/ /*@ assert \forall integer k; j+3 <= k < n ==> a[k] == t[k];*/ /*@ assert same_elements{Pre, Here}(t, t, 0, n);*/ /*@ assert (t[j+1] == x && t[j+2] == y) || (t[j+1] == y && t[j+2] == x);*/ a[j+2] = x; /*@ assert same_elements{Test, Here}(t, t, 0, n);*/ /*@ assert same_elements{Pre, Here}(t, t, 0, n);*/ /*@ assert \forall integer k; j+3 <= k < n ==> a[k] == t[k];*/ /*@ ghost if(t[j+2] == y){t[j+2] = x;t[j+1] = y;} else {} ;*/ /*@ assert \at(t[j+2],Test) == y ==> swap{Test,Here}(t,t, 0,j+1,j+2,n);*/ /*@ assert \at(t[j+2],Test) != y ==> (\forall integer k; 0 <= k < n ==> \at(t[k],Here) == \at(t[k],Test));*/ /*@ assert t[j+2] == x && t[j+1] == y;*/ /*@ assert same_elements{Test, Here}(t, t, 0, n);*/ /*@ assert same_elements{Pre, Here}(t, t, 0, n);*/ /*@ assert \forall integer k; j+2 <= k < n ==> a[k] == t[k];*/ // store x at its insertion place // A[j+1] is an available space now /*@ assert \at(j,Here) == \at(j,Test);*/ /*@ loop invariant \forall integer k, l; 0 <= k <= l <= j ==> a[k] <= a[l]; // the sub-array a[0..j] is sorted loop invariant \forall integer k, l; j+1 < k <= l <= i+1 ==> a[k] <= a[l]; // the sub-array a[j+2..i+1] is sorted loop invariant \forall integer k, l; 0 <= k <= j && j +1 < l <= i+1 ==> a[k] <= a[l]; // every element in a[0..j] is no more then every element in a[j+2..i+1] loop invariant \forall integer k; j+1 < k <= i+1 ==> y <= a[k]; // every element in a[j+2..i+1] is more than x loop invariant -1 <= j <= \at(j, LoopEntry); // j varies between -1 and its value at the loop entry loop invariant same_elements{Pre, Here}(t, t, 0, n); loop invariant \forall integer k; j+1 < k <= i+1 ==> a[k] == t[k]; loop invariant \forall integer k; i+1 < k < n ==> a[k] == t[k]; loop invariant \forall integer k; 0 <= k <= j ==> a[k] == t[k]; loop invariant t[j+1] == y; loop assigns a[0..n-1],j,t[0..n-1]; loop variant j; */ while (j >= 0 && a[j] > y) { // find the insertion point for y /*@ ghost L2:;*/ a[j+1] = a[j]; /*@ ghost int temp = t[j];*/ /*@ ghost t[j] = t[j+1];*/ /*@ ghost t[j+1] = temp;*/ /*@ assert swap{L2, Here}(t, t, 0, j, j+1, n);*/ // shift existing content by 1 j = j - 1; } /*@ ghost Test2:;*/ /*@ assert \forall integer k; j+2 <= k < n ==> a[k] == t[k];*/ /*@ assert same_elements{Pre, Here}(t, t, 0, n);*/ /*@ assert t[j+1] == y;*/ a[j+1] = y; // store y at its insertion place /*@ assert same_elements{Test2, Here}(t, t, 0, n);*/ /*@ assert same_elements{Pre, Here}(t, t, 0, n);*/ /*@ assert \forall integer k; j+1 <= k < n ==> a[k] == t[k];*/ i = i+2; } if (i == n-1) { // if length(A) is odd, an extra int y = a[i]; // single insertion is needed for int j = i - 1; // the last element /*@ loop invariant \forall integer k, l; 0 <= k <= l <= j ==> a[k] <= a[l]; // every element in a[0..j] is more than x loop invariant \forall integer k, l; j+1 < k <= l < n ==> a[k] <= a[l]; // every element in a[j+2..n-1] is more than x loop invariant \forall integer k, l; 0 <= k <= j && j +1 < l < n ==> a[k] <= a[l]; // every element in a[0..j] is no more then every element in a[j+2..n-1] loop invariant \forall integer k; j+1 < k < n ==> y <= a[k]; // every element in a[j+2..n-1] is no less then y loop invariant -1 <= j <= i-1; loop invariant same_elements{Pre, Here}(t, t, 0, n); loop invariant \forall integer k; j+1 < k <= i-1 ==> a[k] == t[k]; loop invariant \forall integer k; i <= k < n ==> a[k] == t[k]; loop invariant \forall integer k; 0 <= k <= j ==> a[k] == t[k]; loop invariant t[j+1] == y; loop assigns a[0..n-1],j,t[0..n-1]; loop variant j; */ while (j >= 0 && a[j] > y) { /*@ ghost L3:;*/ a[j+1] = a[j]; /*@ ghost int temp = t[j];*/ /*@ ghost t[j] = t[j+1];*/ /*@ ghost t[j+1] = temp;*/ /*@ assert swap{L3, Here}(t, t, 0, j, j+1, n);*/ j = j - 1; } /*@ ghost Test3:;*/ /*@ assert \forall integer k; j+2 <= k < n ==> a[k] == t[k];*/ /*@ assert same_elements{Pre, Here}(t, t, 0, n);*/ /*@ assert t[j+1] == y;*/ a[j+1] = y; /*@ assert same_elements{Test3, Here}(t, t, 0, n);*/ /*@ assert same_elements{Pre, Here}(t, t, 0, n);*/ /*@ assert \forall integer k; j+1 <= k < n ==> a[k] == t[k];*/ } //@ assert same_array{Pre, Pre}(a, t, 0, n); //@ assert same_elements{Pre, Here}(t, t, 0, n); //@ assert same_array{Here, Here}(t, a, 0, n); //@ assert same_elements{Pre, Here}(a, a, 0, n); }
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// __deref_in and deref_out #pragma JessieIntegerModel(exact) /*@ requires \valid(ppi) && \valid(ppo) && \valid(*ppi) && \valid(*ppo); @ assigns **ppo; @ ensures **ppo == **ppi; */ void deref_OutAndIn(int **ppi, int **ppo) { **ppo = **ppi; } void deref_OutAndIn_test() { int a = 5; int b = 0; int *pb = &b; int *pa = &a; deref_OutAndIn(&pa, &pb); //@ assert *pa == a; //@ assert *pb == a; }
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#include <limits.h> #include <string.h> /*@ requires ((strlen(x0)>=0) && \valid(x0+(0..strlen(x0)))); */ int matcher_ab_dot_star_ab(char * x0) { int x2 = 0/*false*/; int x3 = 1/*true*/; char *x4 = x0; /*@ loop invariant ((strlen(x4)>=0) && \valid(x4+(0..strlen(x4)))); loop assigns x2, x3, x4; loop variant ((strlen(x4)+((x2) ? (0) : (1)))+((x3) ? (1) : (0))); */ for (;;) { int x5 = x2; int x9; if (x5) { x9 = 0/*false*/; } else { int x7 = x3; x9 = x7; } if (!x9) break; char *x11 = x4; char x12 = x11[0]; int x13 = x12 == '\0'; int x16; if (x13) { x16 = 0/*false*/; } else { int x15 = 'a' == x12; x16 = x15; } int x88; if (x16) { char *x17 = x11+1; char x18 = x17[0]; int x19 = x18 == '\0'; int x22; if (x19) { x22 = 0/*false*/; } else { int x21 = 'b' == x18; x22 = x21; } int x87; if (x22) { int x24 = 0/*false*/; int x25 = 1/*true*/; char *x23 = x17+1; char *x26 = x23; /*@ loop invariant ((strlen(x26)>=0) && \valid(x26+(0..strlen(x26)))); loop assigns x24, x25, x26; loop variant ((strlen(x26)+((x24) ? (0) : (1)))+((x25) ? (1) : (0))); */ for (;;) { int x27 = x24; int x31; if (x27) { x31 = 0/*false*/; } else { int x29 = x25; x31 = x29; } if (!x31) break; char *x33 = x26; char x34 = x33[0]; int x35 = x34 == '\0'; int x38; if (x35) { x38 = 0/*false*/; } else { int x37 = 'a' == x34; x38 = x37; } int x47; if (x38) { char *x39 = x33+1; char x40 = x39[0]; int x41 = x40 == '\0'; int x44; if (x41) { x44 = 0/*false*/; } else { int x43 = 'b' == x40; x44 = x43; } int x46; if (x44) { x46 = 1/*true*/; } else { x46 = 0/*false*/; } x47 = x46; } else { x47 = 0/*false*/; } x24 = x47; int x49 = x24; if (x49) { } else { int x36 = !x35; x25 = x36; int x52 = x25; if (x52) { x25 = 1/*true*/; char *x39 = x33+1; x26 = x39; } else { } } } int x85 = x24; x87 = x85; } else { x87 = 0/*false*/; } x88 = x87; } else { x88 = 0/*false*/; } x2 = x88; int x90 = x2; if (x90) { } else { int x14 = !x13; x3 = x14; int x93 = x3; if (x93) { char *x17 = x11+1; x4 = x17; } else { } } } int x124 = x2; return x124; }
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/* run.config OPT: -cpp-extra-args="-CC" -print */ #define X 1 /* multi-line comment */ + 2 + /* bla */ 3 #define Y 5 + \ 6 + \ 7 /*@ ensures \result == X+Y; */ int main(void) { return X+Y; }
3
#define EQUAL_B_SIZE 5 #define EQUAL_A_SIZE 5 #define ZEROS_A_SIZE 7 /*@ requires \valid(a+(0.. EQUAL_A_SIZE -1)) && EQUAL_A_SIZE >=0 && \valid(b+(0.. EQUAL_B_SIZE -1)) && EQUAL_B_SIZE >=0; assigns \nothing; ensures equal_post : \result ==> (\exists int i; 0 <= i <= EQUAL_A_SIZE-1 && a[i] == b[0]) ; */ int equal(int a[EQUAL_A_SIZE], int b[EQUAL_B_SIZE]) { int res = 1; int i; for (i = 0; i < EQUAL_A_SIZE; i++) { if (a[i] != b[i]) res = 0; } return res; } /*@ requires \valid(a+(0.. ZEROS_A_SIZE -1)) && ZEROS_A_SIZE >=0; assigns a[0.. ZEROS_A_SIZE -1]; ensures zeros_post : \forall int it_x; (0 <= it_x <= ZEROS_A_SIZE-1) ==> \let x=a[it_x];(x == 0) ; */ void zeros(int a[ZEROS_A_SIZE]){ int i; for (int i=0;i<ZEROS_A_SIZE;i++){ a[i]=0; } }
3
/*@ requires n>0; requires 0<=k<n; requires\valid(a+ (0..n-1)); ensures\forall integer i; 0<= i<=k ==>a[k]>=a[i]; */ void bubbleinnerloop(int a[], int n, int k) { /*@ loop invariant\forall integer i; 0<= i<j ==> a[j]>=a[i];loop invariant 0<=j<=k; loop assigns j,a[0..j+1]; loop variant k-j; */ for (int j = 0; j < k; j++) { if (a[j] > a[j + 1]) { int temp = a[j]; a[j] = a[j + 1]; a[j + 1] = temp; } } }
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#include <limits.h> /*@ requires (x0>0); assigns \nothing; ensures ((0<=\result) && (\result<x0)); */ int picker_first(int x0) { return 0; } /*@ requires ((x7>0) && \valid(x6+(0..x7-1))); assigns \nothing; */ int pick_first_element(int * x6, int x7) { int x9 = picker_first(x7); int x10 = x6[x9]; return x10; } /*@ requires ((x16>0) && \valid(x15+(0..x16-1))); assigns \nothing; */ int pick_first_directly(int * x15, int x16) { int x18 = x15[0]; return x18; } /*@ requires (x23>0); assigns \nothing; ensures ((0<=\result) && (\result<x23)); */ int picker_last(int x23) { int x25 = x23 - 1; return x25; } /*@ requires ((x31>0) && \valid(x30+(0..x31-1))); assigns \nothing; */ int pick_last_element(int * x30, int x31) { int x33 = picker_last(x31); int x34 = x30[x33]; return x34; } /*@ requires ((x40>0) && \valid(x39+(0..x40-1))); assigns \nothing; */ int pick_last_directly(int * x39, int x40) { int x42 = x40 - 1; int x43 = x39[x42]; return x43; }
32
#include <string.h> /*@ requires \valid(s + (0..n)); requires valid_string(s); requires c != 0; behavior no_padding: assumes strlen(s) >= n; assigns \nothing; behavior padding: assumes strlen(s) < n; ensures valid_string(s); ensures \let l = strlen{Pre}(s); \let p = n - l; (\forall integer x; 0 <= x < p ==> s[x] == c) && memcmp{Pre, Post}(s, s + p, l + 1) == 0 && strlen(s) == n; assigns s[0 .. n]; complete behaviors; disjoint behaviors; */ void leftpad(char c, size_t n, char *s) { size_t l = strlen(s); if (n > l) { size_t p = n - l; // This loop is equivalent to memmove(s+p, s, l+1) /*@ loop invariant x_range: 0 <= x <= l; loop invariant s_state: \forall integer i; 0 <= i <= n ==> (i <= x+p ==> s[i] == \at(s[i], LoopEntry)) && (i > x+p ==> s[i] == \at(s[i-p], LoopEntry)); loop assigns x, s[p..n]; loop variant x; */ for (size_t x = l;; x--) { s[x+p] = s[x]; if (x == 0) { break; } } // These assertions are not strictly necessary, but they speed up the verification //@ assert same_chars: memcmp{Pre, Here}(s, s+p, l+1) == 0 && s[n] == 0; //@ assert valid_str: valid_string(s+p); //@ assert same_len: strlen(s+p) == l; // This loop is equivalent to memset(s, c, p) /*@ loop invariant x_range2: 0 <= x <= p; loop invariant still_same: memcmp{Pre, LoopCurrent}(s, s+p, l+1) == 0 && s[n] == 0; loop invariant valid_grows: valid_string(s + p - x); loop invariant padding_grows: \forall integer i; p - x <= i < p ==> s[i] == c; loop assigns x, s[0..p-1]; loop variant p - x; */ for (size_t x = 0; x < p; x++) { s[p-1-x] = c; } } }
32
/*@ requires \valid(p) && \valid(q); ensures \result >= *p && \result >= *q; ensures \result == *p || \result == *q; assigns \nothing; */ int max_ptr ( int *p, int *q ) { if ( *p >= *q ) return *p ; return *q ; }
10
#include <stdio.h> #include <stdlib.h> /*@ requires \valid_read(a + (0..n-1)); requires \valid_read(b + (0..n-1)); requires n >= 0; assigns \nothing; behavior if_equal: assumes \forall integer k; 0<=k<n ==> a[k] == b[k]; ensures \result == 1; behavior if_not_equal: assumes \exists integer k;0<=k<n && a[k] != b[k]; ensures \result == 0; */ int equal(int *a, int n, int *b){ int i; i = 0; /*@ loop invariant 0 <= i <= n; loop invariant \forall integer k; 0 <= k < i ==> a[k] == b[k]; loop assigns i; loop variant n-i; */ for (i = 0; i < n; i++) { if (a[i] != b[i]){ return 0; } } return 1; } int main(){ int a[] = {1,2,3,4,5}; int b[] = {1,2,3,4,5}; equal(a,5,b); return 0; }
24
/* Run with: * * frama-c -wp -wp-prover alt-ergo -wp-rte -wp-print -wp-timeout 300 -wp-verbose 0 ex9_final.c -then -report * * Tested with Frama-C Sulfur-20171101. * Η ορθότητα του προγράμματος εξασφαλίζεται πρώτον από το loop invariant της γραμμής 52, που λέει ουσιαστικά ότι, από * όλες τις θέσεις του a που η επανάληψη έχει προσπεράσει, καμία τιμή σε αυτές τις θέσεις * δεν έχει αντίγραφο σε προηγούμενη θέση του a, και δεύτερον από το ensures της γραμμής 38, της οποίας το predicate * ελέγχει για την ορθότητα του αποτελέσματος που επιστρέφεται από τη συνάρτηση. */ #include <stdbool.h> #define MAXV 1000000 /*@ predicate noDouble{L}(int n, int *a) = @ \forall integer i; 0 <= i < n-1 ==> @ \forall integer j; i+1 <= j < n ==> \at(a[i], L) != \at(a[j], L); @*/ /*@ predicate existsDoubleRes{L}(int n, int *a, int res) = @ \exists integer i, j; 0 <= i < j < n ==> res == \at(a[i], L) && res == \at(a[j], L); @*/ /*@ predicate validateResult{L}(int n, int *a, int res) = @ res == 0 ? @ noDouble{L}(n, a) : @ existsDoubleRes{L}(n, a, res); @*/ /*@ requires 0 < N <= MAXV; @ requires \valid(a + (0..(N-1))); @ requires \forall integer i; 0 <= i < N ==> 1 <= a[i] <= MAXV; @ assigns \nothing; @ ensures 0 <= \result <= MAXV; @ ensures validateResult(N, a, \result); @*/ int findDouble(int N, int a[]) { bool f[MAXV]; /*@ loop assigns i, f[0..(MAXV-1)]; @ loop invariant 1 <= i <= (MAXV+1); @ loop invariant \forall integer k; 1 <= k < i ==> f[k-1] == false; @ loop variant MAXV-i; @*/ for (int i = 1; i <= MAXV; ++i) f[i-1] = false; /*@ loop assigns i, f[0..(MAXV-1)]; @ loop invariant 0 <= i <= N; @ loop invariant \forall integer k; 0<=k<i ==> f[a[k]-1] == true; @ loop invariant \forall integer k; 0 < k < i ==> @ \forall integer l; 0 <= l < k ==> a[k] != a[l]; @ loop variant N-i; @*/ for (int i = 0; i < N; ++i) if (f[a[i]-1]) return a[i]; else f[a[i]-1] = true; return 0; }
39
/*@ requires n >= 0; requires \valid(a + (0..n-1)); assigns \nothing; behavior empty: assumes n == 0; ensures \result == 0; behavior not_empty: assumes 0 < n; ensures 0 <= \result < n; ensures \forall integer i; 0 <= i < n ==> a[i] <= a[\result]; ensures \forall integer i; 0 <= i < \result ==> a[i] < a[\result]; complete behaviors; disjoint behaviors; */ int max_element(int* a, int n) { if (n == 0) { return 0; } int max = 0; /*@ loop invariant 0 <= i <= n; loop invariant 0 <= max < n; loop invariant \forall integer k; 0 <= k < i ==> a[k] <= a[max]; loop invariant \forall integer k; 0 <= k < max ==> a[k] < a[max]; loop assigns max, i; loop variant n-i; */ for (int i = 1; i < n; i++) { if (a[max] < a[i]) { max = i; } } return max; } /*@ requires n > 0; requires \valid(p + (0..n-1)); assigns \nothing; ensures \forall integer i; 0 <= i <= n-1 ==> \result >= p[i]; ensures \exists integer e; 0 <= e <= n-1 && \result == p[e]; */ int max_seq(int* p, int n) { return p[max_element(p, n)]; }
36
/*@ requires \valid(p) && \valid(q); requires -10000<*p<10000 && -10000<*q<10000; assigns *p; assigns *q; ensures *p==\old(*q); ensures *q==\old(*p); */ void swap(int *p, int *q){ int sum=*p + *q; *p=sum-*p; *q=sum-*p; }
18
/*@ requires -2147483648<a+b<2147483647; ensures \result==a+b; */ int add(int a,int b){ return a+b ; }
5
/*@ requires n>0; requires \valid_read(a+(0..n-1)); requires \valid_read(b+(0..n-1)); behavior same: assumes \forall integer i; 0<=i<n ==> a[i] == b[i]; ensures \result == 1; behavior not_same: assumes \exists integer i; 0<=i<n && a[i] != b[i]; ensures \result == 0; */ int is_same(int a[],int b[],int n) { /*@ loop invariant \forall integer j; 0<=j<i ==> a[j] == b[j]; loop invariant 0<=i<=n; loop assigns i; loop variant n-i; */ for(int i=0;i<n;i++) { if(a[i] != b[i]) return 0; } return 1; }
14
#include "stddef.h" // the 'pos' pre-condition forbids to pass empty arrays to the function: // otherwise, we would need to make a special case in the code, as initializing // 'high' with 'length - 1' is not a good idea if 'length' is 0 /*@ requires pos: length > 0; requires array: \valid_read(a + (0 .. length - 1)); requires sorted: \forall integer i, j; 0 <= i < j < length ==> a[i] <= a[j]; assigns \nothing; behavior has_key: assumes has_key: \exists integer i; 0 <= i < length && a[i] == key; ensures 0 <= \result < length; ensures a[\result] == key; behavior no_key: assumes no_key: \forall integer i; 0 <= i < length ==> a[i] != key; ensures \result == length; complete behaviors; disjoint behaviors; */ size_t binary_search(char* a, size_t length, char key) { size_t low = 0; size_t high = length - 1; /*@ loop invariant bounds: 0 <= low <= high + 1 <= length; loop invariant small_vals: \forall integer i; 0<=i<low ==> a[i] < key; loop invariant big_vals: \forall integer i; high < i < length ==> a[i] > key; loop assigns high, low; loop variant high - low; */ while (high >= low) { // There was a quite well known bug in the original version of the code: // for big arrays, computing (low + high) / 2 might overflow when doing // the addition, resulting in an incorrect middle index. size_t middle = low + (high - low) / 2; if (a[middle] == key) return middle; if (a[middle] < key) low = middle + 1; else { // another subtle issue of the original code: if we're looking for a // small 'key', 'middle' will eventually become '0', in which case we know // that we won't find 'key'. And of course, we do not want to compute // 'middle - 1' there if (middle == 0) return length; else high = middle - 1; } } return length; }
22
#include <limits.h> /*@ assigns \nothing; ensures (((\result>=x0) && (\result>=x1)) && ((\result==x0) || (\result==x1))); */ int max(int x0, int x1) { int x3 = x0 > x1; int x4; if (x3) { x4 = x0; } else { x4 = x1; } return x4; }
5
#include <limits.h> /*@ requires ((((((((0<x0) && (x0<100)) && (0<x1)) && (x1<100)) && (0<=x2)) && (0<=x3)) && (x2<x0)) && (x3<x1)); assigns \nothing; ensures ((0<=\result) && (\result<(x0*x1))); */ int index(int x0, int x1, int x2, int x3) { int x5 = x2 * x1; int x6 = x5 + x3; return x6; } /*@ predicate inv_matrix_Boolean(int * x36, int x37, int x38) = (((((x37<100) && (x38<100)) && (0<x37)) && (0<x38)) && (((x37*x38)>0) && \valid(x36+(0..(x37*x38)-1))));*/ /*@ requires (((inv_matrix_Boolean(x79,x80,x81) && inv_matrix_Boolean(x82,x83,x84)) && inv_matrix_Boolean(x85,x86,x87)) && ((((x80==x83) && (x80==x86)) && (x81==x84)) && (x81==x87))); ensures ((inv_matrix_Boolean(x79,x80,x81) && inv_matrix_Boolean(x82,x83,x84)) && inv_matrix_Boolean(x85,x86,x87)); */ void add(int * x79, int x80, int x81, int * x82, int x83, int x84, int * x85, int x86, int x87) { /*@ loop invariant 0<=x92<=x86; loop assigns x92, x85[(0..(x86*x87)-1)]; loop variant x86-x92; */ for(int x92=0; x92 < x86; x92++) { /*@ loop invariant 0<=x94<=x87; loop assigns x94, x85[(0..(x86*x87)-1)]; loop variant x87-x94; */ for(int x94=0; x94 < x87; x94++) { int x95 = index(x80,x81,x92,x94); int x96 = x79[x95]; int x97 = index(x83,x84,x92,x94); int x98 = x82[x97]; int x99 = x96 || x98; int x100 = index(x86,x87,x92,x94); x85[x100] = x99; } } } /*@ requires ((inv_matrix_Boolean(x130,x131,x132) && inv_matrix_Boolean(x133,x134,x135)) && ((x131==x134) && (x132==x135))); ensures (inv_matrix_Boolean(x130,x131,x132) && inv_matrix_Boolean(x133,x134,x135)); */ void scalar_mult(int x129, int * x130, int x131, int x132, int * x133, int x134, int x135) { /*@ loop invariant 0<=x140<=x134; loop assigns x140, x133[(0..(x134*x135)-1)]; loop variant x134-x140; */ for(int x140=0; x140 < x134; x140++) { /*@ loop invariant 0<=x142<=x135; loop assigns x142, x133[(0..(x134*x135)-1)]; loop variant x135-x142; */ for(int x142=0; x142 < x135; x142++) { int x145; if (x129) { int x143 = index(x131,x132,x140,x142); int x144 = x130[x143]; x145 = x144; } else { x145 = 0/*false*/; } int x146 = index(x134,x135,x140,x142); x133[x146] = x145; } } }
66
/*@ requires \valid(a) && \valid_read(b); requires \separated(a, b); assigns *a; ensures \old(*b) ==> *a == 0; ensures ! \old(*b) ==> *a == \old(*a); ensures *b == \old(*b); */ void reset_1st_if_2nd_is_true(int* a, int const* b){ if(*b) *a = 0 ; } int main(){ int a = 5 ; int x = 0 ; reset_1st_if_2nd_is_true(&a, &x); //@ assert a == 5 ; //@ assert x == 0 ; int const b = 1 ; reset_1st_if_2nd_is_true(&a, &b); //@ assert a == 0 ; //@ assert b == 1 ; }
18
// pour INT_MIN #include <limits.h> // valeur absolue /*@ requires a != INT_MIN; ensures \result >= 0; ensures \result == a || \result == -a; */ int abs(int a) { return (a > 0) ? a : -a; }
5
// __in struct pointer typedef struct s { int a; int b; } S; /*@ requires \valid(ps); @ assigns ps->b; */ void f6(S *ps) { if (ps) { if (ps->a == 0) { ps->b = 0; } else { ps->b = 1; } } }
7
/*@ ensures 0 <= \result <= 1;*/ // */ int loop(unsigned N) { int c = 0; unsigned i; /*@ loop invariant 0 <= c <= 1; loop invariant i <= N; loop variant N - i; */ for (i = 0; i < N; ++i) { c = 1 - c; } return c; }
10
/*@ axiomatic GCD { @ logic integer gcd(integer x, integer y); @ axiom gcd_equal: @ \forall integer x; @ (x > 0) ==> gcd(x, x) == x; axiom gcd_comm: \forall integer x, integer y; (x > 0 && y > 0) ==> gcd(x, y) == gcd(y, x); axiom gcd_add: \forall integer x, integer y; (x > 0 && y > 0) ==> gcd(x + y, y) == gcd(x, y); @ } */ /*@ requires a > 0 && b > 0; @ assigns \nothing; @ ensures \result == gcd(a, b); */ int euclid(int a, int b) { int x = a; int y = b; /*@ loop invariant x > 0 && y > 0; @ loop invariant gcd(x, y) == gcd(a,b); @ loop assigns x, y; @ loop variant \max(x, y); */ while (x != y) { if (x > y) { x -= y; } else { y -= x; } } return x; }
15
#define SPEC_INT_MIN -2147483648 #define SPEC_INT_MAX 2147483647 /*@ requires \true; requires a > SPEC_INT_MIN; // Найдите ошибку в спецификации. Ответ. requires b > SPEC_INT_MIN; // Найдите ошибку в спецификации. Ответ. assigns \nothing; ensures \result == \abs(\abs(a) - \abs(b)); */ unsigned distance_abs(int a, int b) { unsigned ua = a < 0 ? -a : a; unsigned ub = b < 0 ? -b : b; //unsigned ua = a < 0 ? ((unsigned)-((long)a)) : a; // Найдите ошибку в реализации. Ответ. //unsigned ub = b < 0 ? ((unsigned)-((long)b)) : b; // Найдите ошибку в реализации. Ответ. return ua > ub ? ua - ub : ub - ua; } #ifdef OUT_OF_TASK #include <stdio.h> int main(void) { printf("res: %u\n", distance_abs(3,30)); printf("res: %u\n", distance_abs(-5,-20)); printf("res: %u\n", distance_abs(7,-10)); printf("res: %u\n", distance_abs(-2,15)); return 0; } #endif
11
/*@ requires n>0; requires \valid(t+(0..n-1)); ensures \forall integer i; 0<=i<n ==> t[\result]<=t[i]; ensures \exists integer i; 0<=i<n && t[\result]<=t[i]; */ int minarray(int t[],int n) { int index=0; /*@ loop invariant 0<=i<=n; loop invariant 0<=index<n; loop invariant \forall integer j; 0<=j<i ==> t[index]<=t[j]; loop variant n-1-i; */ for(int i=0;i<n;i++) { if ( t[i] < t[index] ) index = i; } return index; }
11
/*@ predicate inInterval(integer a, integer b, integer c) = a >= b && b <= c; predicate fourInOrder(integer a, integer b, integer c, integer d) = inInterval(b,a,c) && inInterval(c,b,d); predicate controlledEquality(integer a, integer b, boolean c) = a == b || c; */ /*@ requires inInterval(a,b,c); requires inInterval(c,a,d); ensures fourInOrder(\result,a,c,d); */ int toto(int a, int b, int c, int d){ return b; }
3
// Note axiomatization with integer type, rather than int. /* inductive isfact(integer n, integer r) { @ case isfact0: @ isfact(0,1); @ case isfactn: @ \forall integer n, integer f; @ isfact(n-1,f) ==> isfact(n,f*n); @ } @*/ /* axiomatic factorial { @ @ logic integer fact (integer n); @ @ axiom fact1: @ \forall integer n; isfact (n,fact(n)); @ @ axiom fact2: @ \forall integer n, integer f; isfact (n,f) ==> f==fact(n); @ } @ @*/ /*@ logic integer fact (integer n) = @ (n == 0) ? 1 : n * fact(n-1); @ @*/ /*@ requires n >= 0; @ ensures fact(n) == \result; @ assigns \nothing; @*/ int factf (int n) { int f = 1; int i = 1 ; /*@ loop invariant 1 <= i <= n+1 && f == fact(i-1); @ loop assigns i, f; @ loop variant n-i; @*/ while (i <= n) { f = f * i; i = i + 1; } return f; }
3
/*@ requires i > sizeof(int); @ ensures \result > sizeof(i); @*/ int f(int i) { return i; }
3
#include <limits.h> /*@ predicate inv_vec_Int(int * x0, integer x1) = ((x1==0) || ((x1>0) && \valid(x0+(0..x1-1))));*/ /*@ predicate eq_vec_Int(int * x15, int x16, int * x17, int x18) = ((x16==x18) && (\forall int x22; (0<=x22<x16) ==> (x15[x22]==x17[x22])));*/ /*@ requires (inv_vec_Int(x15,x16) && inv_vec_Int(x17,x18)); assigns \nothing; ensures (inv_vec_Int(x15,x16) && inv_vec_Int(x17,x18)); ensures \result <==> eq_vec_Int(x15, x16, x17, x18); */ int eq_vec_Int(int * x15, int x16, int * x17, int x18) { int x20 = x16 == x18; int x31; if (x20) { int x30 = 1; /*@ loop invariant (0 <= x23 <= x16); loop invariant \forall int x22; (0 <= x22 < x23) ==> (x15[x22]==x17[x22]); loop invariant x30==1; loop assigns x23, x30; loop variant (x16-x23); */ for (int x23 = 0; x23 < x16; x23++) { int x27 = x15[x23]; int x28 = x17[x23]; int x29 = x27 == x28; if (!x29) { x30 = 0; break; } } x31 = x30; } else { x31 = 0/*false*/; } return x31; }
20
/*@ ensures (((((b*b)-4*a*c)>=0)&&(\result==0))||((((b*b)-4*a*c)<0)&&(\result==1))); */ int check(int a, int b, int c) { if(((b*b)-(4*a*c))>=0) return 0; else return 1; } int main() { int ret = check(2,1,1); return 0; }
20
#include <stddef.h> /*@ requires \valid(s + (0 .. length - 1)); requires \valid(stack + (0 .. length - 1)); requires \valid(left + (0 .. length - 1)); requires \separated(stack + (0 .. length - 1),left + (0 .. length - 1)); requires \separated(stack + (0 .. length - 1), s + (0 .. length - 1)); requires \separated(left + (0 .. length - 1), s + (0 .. length - 1)); assigns stack[0 .. length - 1], left[0 .. length - 1]; ensures wf_left: \forall integer i; 0 <= i < length ==> 0 <= left[i] <= i; ensures left_small: \forall integer i; 0 <= i < length ==> 0 < left[i] ==> left[i] > 0 ==> s[left[i]-1] < s[i]; ensures left_smallest: \forall integer i; 0 <= i < length ==> \forall integer j; left[i] <= j < i ==> s[j] >= s[i]; */ void neighbor(int* s, size_t length, size_t* stack, size_t* left) { size_t sidx = 0; /*@ loop invariant s_untouched: \forall integer idx; 0 <= idx < length ==> s[idx] == \at(s[idx],Pre); loop invariant 0 <= x <= length; loop invariant 0 <= sidx <= x; loop invariant stack_left: \forall integer i; 0 <= i < sidx ==> 0 < stack[i] <= x; loop invariant wf_left: \forall integer i; 0 <= i < x ==> 0 <= left[i] <= i; loop invariant left_small: \forall integer i; 0 <= i < x ==> left[i] > 0 ==> s[left[i] - 1] < s[i]; loop invariant left_smallest: \forall integer i; 0 <= i < x ==> \forall integer j; left[i] <= j < i ==> s[j] >= s[i]; loop invariant stack_order: \forall integer i, j; 0<= i < j < sidx ==> 0 <= stack[i] < stack[j]; loop invariant stack_sorder: \forall integer i, j; 0<= i < j < sidx ==> s[stack[i]-1] < s[stack[j]-1]; loop invariant s_begin: sidx > 0 ==> \forall integer i; 0<=i<stack[0] ==> s[i] >= s[stack[0] - 1]; loop invariant step_n: x > 0 ==> sidx > 0 && stack[sidx - 1] == x; loop invariant stack_summary: \forall integer i; 0<= i < sidx - 1 ==> \forall integer j; stack[i] <= j < stack[i+1]-1 ==> s[j] >= s[stack[i+1]-1]; loop invariant stack_push: sidx > 0 ==> stack[sidx-1] == x; loop assigns x, sidx, stack[0 .. length - 1], left[0 .. length - 1]; loop variant length - x; */ for (size_t x = 0; x < length; x++) { /*@ loop invariant s_untouched_inner: \forall integer idx; 0 <= idx < length ==> s[idx] == \at(s[idx],Pre); loop invariant 0 <= sidx <= \at(sidx,LoopEntry); loop invariant left_bigger: sidx > 0 ==> \forall integer i; stack[sidx-1] <= i < x ==> s[i] >= s[x]; loop invariant stack_empty: sidx == 0 ==> \forall integer i; 0 <= i < x ==> s[i] >= s[x]; loop assigns sidx; loop variant sidx; */ while (sidx > 0 && s[stack[sidx-1]-1] >= s[x]) sidx--; if (sidx == 0) { left[x] = 0; } else { /*@ assert head_ok: \forall integer i; stack[sidx-1]<=i<x ==> s[i] >= s[x]; */ left[x] = stack[sidx - 1]; } //@ assert a1: left[x] > 0 ==> s[left[x] - 1] < s[x]; label: stack[sidx] = x + 1; /*@ assert s_untouched: \forall integer idx; 0 <= idx < length ==> s[idx] == \at(s[idx],Pre); */ //@ assert same: left[x] == \at(left[x], label); //@ assert a2: left[x] > 0 ==> s[left[x] - 1] < s[x]; sidx++; } }
62
/* run.config DONTRUN: linked with first which is the real test. */ /*@ behavior b: requires \valid(third); ensures \result == 0;*/ int bar(int *third) { third=(int*)*third; return 0; }
4
/*@ predicate pcond1(integer p) = (p>0)?\true:\false ; @ predicate pcond2(integer p) = (p<10)?\true:\false ; @*/ /*@ //// ensures (pcond1(x) && pcond2(y)) ==> \result == 1 ; @ ensures \result == 1 <==> pcond1(x) && pcond2(y); @*/ int ftest1(int x, int y) { return (x>0 && y<10); } /*@ predicate pcond3(integer p) = p > 0; @ predicate pcond4(integer p) = p < 10; @*/ /*@ behavior ok: @ assumes pcond3(x) && pcond4(y); @ ensures \result == 1; @ behavior ko: @ assumes !pcond3(x) || !pcond4(y); @ ensures \result == 0; @*/ int ftest2(int x, int y) { return (x>0 && y<10); }
7
/*@ ensures *q == \old(*p) && *p == \old(*q) ; assigns *p,*q; */ void f (int *p,int*q) { int t = *p; *p = *q; *q = t; return; }
7
/*@ requires n > 0; @ ensures \result == \max(0,n-1,\lambda integer k; t[k]); @*/ double max_array(double t[], int n) { double m; int i=0; goto L; do { if (t[i] > m) { L: m = t[i]; } /*@ invariant @ 0 <= i < n && m == \max(0,i,\lambda integer k; t[k]); @*/ i++; } while (i < n); return m; }
1
#include<stdio.h> enum kind {vowel,consonent}; /*@ requires c>='a' && c<='z'; behavior vowel: assumes c=={'a','e','i','o','u'}; ensures \result==vowel; behavior consonent: assumes c=={'b','c','d','f','g','h','j','k','l','m','n','p','q','r','s','t','v','w','x','y','z'}; ensures \result==consonent; disjoint behaviors; */ enum kind kind_of_letter(char c){ if(c=='a' || c=='e' || c=='i' || c=='o' || c=='u'){ return vowel; } else{ return consonent; } } /*@ behavior q1: assumes x>=0 &&y>0; ensures \result==1; behavior q2: assumes x<0 &&y>=0; ensures \result==2; behavior q3: assumes x<=0 &&y<0; ensures \result==3; behavior q4: assumes x>0 &&y<=0; ensures \result==4; behavior q0: assumes x==0 &&y==0; ensures \result==0; complete behaviors; */ int quadrant(int x,int y){ /* *Basically remember to check for the logical constrains of quadrants */ if(x>=0 && y>0) return 1; else if (x<0 && y>=0) return 2; else if (x<=0 && y<0) return 3; else if (x==0 && y==0) return 0; else return 4; }
13
/*@ predicate Positive(int a) = 0 < a; */ /*@ predicate Positive(short a) = 0 < a; */ /*@ requires Positive(a); assigns \nothing; ensures Positive(\result); */ int foo(short a) { return a; } struct Pair { int first, second; }; typedef struct Pair Pair; /*@ predicate Positive(Pair p) = Positive(p.first) && Positive(p.second); */ /*@ requires Positive(a); assigns \nothing; ensures Positive(\result); */ Pair bar(int a) { Pair p; p.first = a; p.second = a; return p; }
9
// Side effects can be controlled on an individual basis. #include <limits.h> extern int a; /*@ requires x > INT_MIN; assigns a; // allow assignment to a (but only to a). ensures 0 <= x ==> \result == x; ensures 0 > x ==> \result == -x; */ int abs_int(int x) { a = x; return (x >= 0) ? x : -x; }
8
/*@ requires \valid(a) && \valid(b); assigns *a, *b; ensures *a == \old(*b) && *b == \old(*a); */ void swap(int* a, int* b) { int tmp = *a; *a = *b; *b = tmp; } int main(){ int a = 37; int b = 91; swap(&a, &b); }
12
/*@ //requires \nothing; requires \true; assigns \nothing; ensures \result == \max(a, b) - \min(a, b); */ unsigned distance(unsigned a, unsigned b) { return (a > b) ? (a - b) : (b - a); } #ifdef OUT_OF_TASK #include <stdio.h> int main(void) { printf("res: %d\n", distance(100, 80)); return 0; } #endif
5
#include <limits.h> /*@ requires \valid(x0+(0..1)); ensures ((x0[0]==\old(x0[1])) && (x0[1]==\old(x0[0]))); */ void array_swap(int * x0) { int x2 = x0[0]; int x3 = x0[1]; x0[0] = x3; x0[1] = x2; }
7
/*@ requires \valid(p); ensures *p == 0; */ void main(int*p) { *p = 0; CEA_DUMP(); }
7
/*@ requires d > 0; assigns \nothing; ensures 0 <= \result < d; */ static inline unsigned int inverse_modulo(unsigned int n, unsigned int d) { return d - 1 - (n % d); }
5
/*@ ensures \result >= x && \result >= y; ensures \result == x || \result == y; */ int max (int x, int y) { return (x > y) ? x : y; }
4
/*@ predicate sorted(int *t,integer i,integer j) = @ \forall integer k, integer l; i <= k < l <= j ==> t[k] <= t[l]; @*/ /*@ requires N >= 1 && \valid(A+(0..N-1)); @ assigns A[0..N-1]; @ ensures sorted(A,0,N-1); @*/ void insertionSort(int A[], int N) { int i, j, key; /*@ loop invariant @ 1 <= j <= N && sorted(A, 0, j-1); @ loop assigns @ j, key, i, A[0..N-1]; @ loop variant @ N-j; @*/ for (j=1 ; j<N ; j++) { key = A[j]; i = j-1; /*@ loop invariant -1 <= i <= j-1; @ loop invariant i == j-1 ==> sorted(A, 0, j-1); @ loop invariant i < j-1 ==> sorted(A, 0, j); @ loop invariant \forall int k; i < k < j ==> A[k] > key; @ loop assigns i, A[1..j]; @ loop variant i; @*/ while (i>=0 && A[i] > key) { A[i+1] = A[i]; i--; } A[i+1] = key; } }
36
#pragma JessieIntegerModel(math) /*@ logic integer POW (integer x, integer n) = @ (n > 0) ? x * POW(x, n-1) @ : 1; @*/ /*@ requires n >= 0; @ ensures \result == POW(x, n); @*/ unsigned long pow (unsigned long x, unsigned int n) { unsigned long r; /*@ loop invariant n >= 0; @ loop invariant r * POW(x, n) == \at(POW(x, n), Pre); @ loop variant n; @*/ for (r = 1; n > 0; n /= 2, x = x*x) if (n % 2 == 1) r *= x; return r; } /*@ lemma pow_zero: @ \forall integer x; @ POW(x, 0) == 1; @*/ /*@ lemma pow_square_odd: @ \forall integer x, integer n; @ n >= 0 ==> @ n % 2 == 1 ==> @ POW(x, n) == x * POW(x*x, n/2); @*/ /*@ lemma pow_square_even: @ \forall integer x, integer n; @ n >= 0 ==> @ n % 2 == 0 ==> @ POW(x, n) == POW(x*x, n/2); @*/
36
/*@ requires \pointer_comparable((void*)p,(void*)q) && \is_finite(*p) ; */ void f(float*p, char const * q) { return; }
2
/*@ requires n > 0; requires \valid(a+(0..n-1)); requires \valid(b+(0..n-1)); assigns \nothing; behavior same: assumes \forall integer k; 0 <= k < n ==> a[k] == b[k]; ensures \result==1; behavior different: assumes \exists integer k; 0 <= k < n && a[k] != b[k]; ensures \result==0; complete behaviors same, different; disjoint behaviors same, different; */ /* NOTE : the opposite of the proposition \forall integer k; 0 <= k < n ==> a[k] == b[k] is the proposition \exists integer k; 0 <= k < n && a[k] != b[k] INDEED ! - the negation of (A ==> B) is A && (negation of B) - seen from another point of view, "the negation of forall k, A" is "exists k, the negation of A" (this is 100% logical if you think of it a bit) */ int equal(const int* a, int n, const int* b) { /*@ loop invariant 0 <= i <= n; loop invariant \forall integer k; 0 <= k < i ==> a[k] == b[k]; loop assigns i; loop variant n-i; */ for(int i=0; i<n; i++) { if (a[i] != b[i]) { return 0; } } return 1; }
19
/*@ requires \valid(t+(0..n-1)) && n > 0; @ ensures (\forall integer i; 0 <= i < n ==> \result <= t[i]) && @ (\exists integer i; 0 <= i < n && \result == t[i]); @ assigns \nothing; */ int getMin(int t[], int n) { int res = t[0]; /*@ loop invariant 1 <= i <= n && @ (\forall integer j; 0 <= j < i ==> res <= t[j]) && @ (\exists integer j; 0 <= j < i && res == t[j]); @ loop assigns i, res; @ loop variant n - i; @*/ for (int i = 1; i < n; i++) { if (t[i] < res) res = t[i]; } return res; }
13
/*@ requires b != 0; requires b != -1; assigns \nothing; ensures \result == a / b; */ int divide(int a, int b) { return a / b; }
6
#include <limits.h> /*@ requires (((x1>0) && \valid(x0+(0..x1-1))) && \valid(x2+(0..x1-1))); ensures ((((0<=\result) && (\result<=x1)) && (\forall int x74; (((0<=x74) && (x74<\result)) ==> ((0<=x2[x74]) && (x2[x74]<x1))))) && (\forall int x86; (((0<x86) && (x86<\result)) ==> (x2[(x86-1)]<x2[x86])))); assigns x2[(0..x1-1)]; */ int index_where_even(int * x0, int x1, int * x2) { int x5 = 0; /*@ loop invariant ((((((0<=x6) && (x6<=x1)) && (0<=x5)) && (x5<=x6)) && (\forall int x28; (((0<=x28) && (x28<x5)) ==> ((0<=x2[x28]) && (x2[x28]<x6))))) && (\forall int x42; (((0<x42) && (x42<x5)) ==> (x2[(x42-1)]<x2[x42])))); loop assigns x6, x5, x2[(0..x1-1)]; loop variant (x1-x6); */ for(int x6=0; x6 < x1; x6++) { int x7 = x0[x6]; int x8 = x7 % 2; int x9 = x8 == 0; if (x9) { int x10 = x5; x2[x10] = x6; x5 += 1; } else { } } int x62 = x5; return x62; }
15
#include <stdlib.h> /*@ requires n >= 0 && n <= 100; ensures \result >= 0; ensures \result == (int)((n+1)*(n)/2); assigns \nothing; */ int sum(char n) { int s = 0; char k = 0; /*@ loop invariant 0 <= k <= n+1; loop invariant s == (k-1)*(k)/2; loop assigns k, s; loop variant n - k; */ while(k <= n) { s = s + (int)k; k = k + 1; } return (int)s; } int main() { int s = sum(5); //@ assert s == 15; }
19
#include<stdio.h> /*@ requires \valid(a) && \valid(b) && \valid(c) ; requires \separated(a, b, c); assigns *a, *b, *c ; ensures *a <= *b <= *c ; ensures { *a, *b, *c } == \old({ *a, *b, *c }) ; ensures \old(*a == *b == *c) ==> *a == *b == *c ; ensures \old(*a == *b < *c || *a == *c < *b || *b == *c < *a) ==> *a == *b ; ensures \old(*a == *b > *c || *a == *c > *b || *b == *c > *a) ==> *b == *c ; */ void order_3(int* a,int* b,int* c){ if(*a > *b){int tmp = *b ;*b = *a ;*a = tmp ; } if(*a > *c){int tmp = *c ; *c = *a ;*a = tmp ; } if(*b > *c){int tmp = *b ;*b = *c ;*c = tmp ;} } void test(){ int a1 =5, b1=3, c1=4; order_3(&a1, &b1, &c1) ; //@ assert a1 == 3 && b1 == 4 && c1 == 5 ; int a2 =2, b2=2, c2=2; order_3(&a2, &b2, &c2) ; //@ assert a2 == 2 && b2 == 2 && c2 == 2 ; int a3 =4, b3=3, c3=4; order_3(&a3, &b3, &c3) ; //@ assert a3 == 3 && b3 == 4 && c3 == 4 ; int a4 =4, b4=5, c4=4; order_3(&a4, &b4, &c4) ; //@ assert a4 == 4 && b4 == 4 && c4 == 5 ; }
45
// =================== Exercies 1 =================== /*@ @ ensures \result >= a; @ ensures \result >= b; @ ensures \result >= c; @ ensures \result == a || \result == b || \result == c; @ assigns \nothing; */ int max3(int a, int b, int c) { if (a >= b && a >= c) return a; if (b >= b && b >= c) return b; return c; } // =================== Exercies 2 =================== /*@ @ requires 0 < n <= 100000000; @ requires \valid(t+(0..n - 1)); @ @ ensures \forall int i; 0 <= i < n ==> t[i] == 2 * i; */ void double_(int t[], int n) { /*@ @ loop invariant 0 <= i <= n; @ loop invariant \forall int j; 0 <= j < i ==> t[j] == 2 * j; @ loop variant n - i; */ for (int i = 0; i < n; ++i) { t[i] = 2 * i; } } // =================== Exercies 3 =================== /*@ @ requires \valid(arr+(0.. n - 1)); @ requires n > 0; @ @ assigns \nothing; @ behavior true_: @ assumes \forall int i; 1 <= i < n ==> arr[i] > arr[i - 1]; @ ensures \result == 1; @ behavior false_: @ assumes \exists int i; 1 <= i < n && arr[i] <= arr[i - 1]; @ ensures \result == 0; */ int increasing(int arr[], int n) { /*@ @ loop invariant 1 <= i <= n; @ loop invariant \forall int j; 1 <= j < i ==> arr[j] > arr[j - 1]; @ loop variant n - i; */ for (int i = 1; i < n; ++i) { if (arr[i] <= arr[i - 1]) return 0; } return 1; } // =================== Exercies 4 =================== /*@ @ requires \valid(arr+(0.. n - 1)); @ requires n > 0; @ @ assigns \nothing; @ behavior true_: @ assumes \forall int i; 1 <= i < n ==> arr[i] < arr[i - 1]; @ ensures \result == 1; @ behavior false_: @ assumes \exists int i; 1 <= i < n && arr[i] >= arr[i - 1]; @ ensures \result == 0; */ int decreasing(int arr[], int n) { /*@ @ loop invariant 1 <= i <= n; @ loop invariant \forall int j; 1 <= j < i ==> arr[j] < arr[j - 1]; @ loop variant n - i; */ for (int i = 1; i < n; ++i) { if (arr[i] >= arr[i - 1]) return 0; } return 1; } /*@ @ requires \valid(arr+(0.. n - 1)); @ requires n > 0; @ @ assigns \nothing; @ behavior increaing: @ assumes \forall int i; 1 <= i < n ==> arr[i] > arr[i - 1]; @ ensures \result == 1; @ behavior decreasing: @ assumes \forall int i; 1 <= i < n ==> arr[i] < arr[i - 1]; @ ensures \result == -1; @ behavior none: @ assumes \exists int i; 1 <= i < n && arr[i] <= arr[i - 1]; @ assumes \exists int i; 1 <= i < n && arr[i] >= arr[i - 1]; @ ensures \result == 0; */ int monotomic(int arr[], int n) { if (increasing(arr, n)) return 1; if (decreasing(arr, n)) return -1; return 0; }
34
/*@ inductive is_gcd(integer a, integer b, integer d) { case gcd_zero: \forall integer n; is_gcd(n,0,n); case gcd_succ: \forall integer a,b,d; is_gcd(b, a % b, d) ==> is_gcd(a,b,d); } */ /*@ axiomatic gcd { logic integer gcd(integer a, integer b); axiom nil: \forall integer n; gcd(n,0) == n; axiom next: \forall integer a,b; gcd(b, a % b) == gcd(a,b); } */ /*@ decreases b; assigns \nothing; ensures is_gcd(a, b, \result); ensures \result == gcd(a, b); */ unsigned gcd_rec(unsigned a, unsigned b) { if (b == 0) return a; return gcd_rec(b, a % b); }
11
#include <limits.h> /*@ predicate inv_vec_Int(int * x0, integer x1) = ((x1==0) || ((x1>0) && \valid(x0+(0..x1-1))));*/ /*@ predicate eq_vec_Int(int * x15, int x16, int * x17, int x18) = ((x16==x18) && (\forall int x22; (0<=x22<x16) ==> (x15[x22]==x17[x22])));*/ /*@ requires (inv_vec_Int(x15,x16) && inv_vec_Int(x17,x18)); assigns \nothing; ensures (inv_vec_Int(x15,x16) && inv_vec_Int(x17,x18)); ensures \result <==> eq_vec_Int(x15, x16, x17, x18); */ int eq_vec_Int(int * x15, int x16, int * x17, int x18) { int x20 = x16 == x18; int x31; if (x20) { int x30 = 1; /*@ loop invariant (0 <= x23 <= x16); loop invariant \forall int x22; (0 <= x22 < x23) ==> (x15[x22]==x17[x22]); loop invariant x30==1; loop assigns x23, x30; loop variant (x16-x23); */ for (int x23 = 0; x23 < x16; x23++) { int x27 = x15[x23]; int x28 = x17[x23]; int x29 = x27 == x28; if (!x29) { x30 = 0; break; } } x31 = x30; } else { x31 = 0/*false*/; } return x31; } /*@ predicate inv_vec_vec_Int(int * * x35, int * x36, integer x37) = (((x37==0) || ((x37>0) && (\valid(x35+(0..x37-1)) && \valid(x36+(0..x37-1))))) && (\forall int x47; (0<=x47<x37) ==> inv_vec_Int(x35[x47],x36[x47])));*/ /*@ predicate eq_vec_vec_Int(int * * x58, int * x59, int x60, int * * x61, int * x62, int x63) = ((x60==x63) && (\forall int x67; (0<=x67<x60) ==> eq_vec_Int(x58[x67],x59[x67],x61[x67],x62[x67])));*/ /*@ requires (inv_vec_vec_Int(x58,x59,x60) && inv_vec_vec_Int(x61,x62,x63)); assigns \nothing; ensures (inv_vec_vec_Int(x58,x59,x60) && inv_vec_vec_Int(x61,x62,x63)); ensures \result <==> eq_vec_vec_Int(x58, x59, x60, x61, x62, x63); */ int eq_vec_vec_Int(int * * x58, int * x59, int x60, int * * x61, int * x62, int x63) { int x65 = x60 == x63; int x80; if (x65) { int x79 = 1; /*@ loop invariant (0 <= x68 <= x60); loop invariant \forall int x67; (0 <= x67 < x68) ==> eq_vec_Int(x58[x67],x59[x67],x61[x67],x62[x67]); loop invariant x79==1; loop assigns x68, x79; loop variant (x60-x68); */ for (int x68 = 0; x68 < x60; x68++) { int *x74 = x58[x68]; int x75 = x59[x68]; int *x76 = x61[x68]; int x77 = x62[x68]; int x78 = eq_vec_Int(x74,x75,x76,x77); if (!x78) { x79 = 0; break; } } x80 = x79; } else { x80 = 0/*false*/; } return x80; }
48
/*@ assigns \nothing; ensures \result == a / 2; */ unsigned rshift(unsigned a) { return a >> 1; }
4
#include <stdint.h> #include <stddef.h> #define NUM_ELEMS (8) /*@ requires expected != test; @ requires \let n = NUM_ELEMS; @ \valid_read(expected + (0.. n-1)) && \valid_read(test + (0.. n-1)); @ assigns \nothing; @ behavior matches: @ assumes \let n = NUM_ELEMS; @ \forall integer i; 0 <= i < n ==> expected[i] == test[i]; @ ensures \result == 1; @ behavior not_matches: @ assumes \let n = NUM_ELEMS; @ \exists integer i; 0 <= i < n && expected[i] != test[i]; @ ensures \result == 0; @ complete behaviors; @ disjoint behaviors; @*/ int array_equals(const uint32_t expected[static NUM_ELEMS], const uint32_t test[static NUM_ELEMS]) { /*@ loop invariant \let n = NUM_ELEMS; 0 <= i <= n; @ loop invariant \forall integer k; 0 <= k < i ==> expected[k] == test[k]; @ loop assigns i; @ loop variant \let n = NUM_ELEMS; n-i; @*/ for (size_t i = 0; i < NUM_ELEMS; i++) { if (expected[i] != test[i]) { return 0; } } return 1; }
18
// Program to find index of an element in an array // Behaviors not used in this program /*@ requires n >= 0; requires \valid_read(arr+(0..n-1)); assigns \nothing; ensures -1 <= \result < n; ensures 0 <= \result < n ==> arr[\result] == x; ensures (\result == -1) ==> (\forall integer i; 0 <= i < n ==> arr[i] != x); assigns \nothing; */ int array_find(int* arr, int n, int x) { int i = 0; /*@ loop invariant 0 <= i <= n; loop invariant \forall integer k; 0 <= k < i ==> arr[k] != x; loop assigns i; loop variant n-i; */ for (i = 0; i < n; i++) { if (arr[i] == x) { return i; } } return -1; } // from this directory run: frama-c-gui -wp array_find.c
18
#include <limits.h> /*@ requires ((x1>0) && \valid(x0+(0..x1-1))); assigns \nothing; ensures (((\result==-1) ==> (!(\exists int x56; (((0<=x56) && (x56<x1)) && (x0[x56]==x2))))) && ((\result!=-1) ==> (((0<=\result) && (\result<x1)) && (x0[\result]==x2)))); */ int member(int * x0, int x1, int x2) { int x4 = -1; /*@ loop invariant ((((0<=x6) && (x6<=x1)) && ((x4==-1) ==> (!(\exists int x22; (((0<=x22) && (x22<x6)) && (x0[x22]==x2)))))) && ((x4!=-1) ==> (((0<=x4) && (x4<x6)) && (x0[x4]==x2)))); loop assigns x6, x4; loop variant (x1-x6); */ for(int x6=0; x6 < x1; x6++) { int x7 = x4; int x8 = x7 == -1; int x11; if (x8) { int x9 = x0[x6]; int x10 = x9 == x2; x11 = x10; } else { x11 = 0/*false*/; } if (x11) { x4 = x6; } else { } } int x50 = x4; return x50; }
13
#include <limits.h> /*@ predicate inv_vec_Int(int * x0, int x1) = ((x1==0) || ((x1>0) && \valid(x0+(0..x1-1))));*/ /*@ predicate eq_vec_Int(int * x16, int x17, int * x18, int x19) = ((x17==x19) && (\forall int x23; (0<=x23<x17) ==> (x16[x23]==x18[x23])));*/ /*@ requires (inv_vec_Int(x16,x17) && inv_vec_Int(x18,x19)); assigns \nothing; ensures (inv_vec_Int(x16,x17) && inv_vec_Int(x18,x19)); ensures \result <==> eq_vec_Int(x16, x17, x18, x19); */ int eq_vec_Int(int * x16, int x17, int * x18, int x19) { int x21 = x17 == x19; int x33; if (x21) { int x32 = 1; /*@ loop invariant (0 <= x24 <= x17); loop invariant \forall int x23; (0 <= x23 < x24) ==> (x16[x23]==x18[x23]); loop assigns x24; loop variant (x17-x24); */ for (int x24 = 0; x24 < x17; x24++) { int x29 = x16[x24]; int x30 = x18[x24]; int x31 = x29 == x30; if (!x31) { x32 = 0; break; } } x33 = x32; } else { x33 = 0/*false*/; } return x33; }
18
/*@ predicate swapped{L1,L2}(int *a, int *b) = \at(*a, L2) == \at(*b,L1) && \at(*b, L2) == \at(*a,L1); */ /*@ requires \valid(a); requires \valid(b); assigns *a, *b; ensures swapped{Pre, Post}(a, b); */ void swap(int *a, int *b) { int tmp = *a; *a = *b; *b = tmp; }
9
typedef enum{ VRAI=1, FALSE=0 }T_BOOLEEN; /*@logic T_BOOLEEN test (integer b)= @ @ ((b==1)? @ (T_BOOLEEN)VRAI @ : (T_BOOLEEN)FALSE); @*/ /*@ensures \result == test(boo); @*/ T_BOOLEEN test(int boo) { T_BOOLEEN b; if (boo==1) b = VRAI; else b= FALSE; return b; }
3
/* * Nikos Mavrogeorgis 03113087 * Frama-C version : Sulfur-20171101 */ #include <stdbool.h> #define MAXV 1000000 /*@ @ requires 1 <= N; @ requires \valid (a + (0 .. N - 1)); @ requires \forall integer i; 0 <= i < N ==> 1 <= a[i] <= MAXV; @ ensures \result != 0 <==> \exists integer i, j; 0 <= i < j < N && a[i] == a[j] == \result; @*/ int findDouble(int N, int a[]) { bool f[MAXV]; /*@ @ loop invariant \let n = MAXV; 1 <= i <= n + 1; @ loop invariant \forall integer k; 1 <= k < i ==> f[k-1] == false; @ loop assigns i, f[0 .. (i - 1)]; @ loop variant \let n = MAXV; n-i; @*/ for (int i = 1; i <= MAXV; ++i) f[i-1] = false; /*@ @ loop invariant 0 <= i <= N; @ loop invariant \let n = MAXV; \forall integer k; 1 <= k <= n ==> @ (f[k-1] <==> \exists integer j; 0 <= j < i && a[j] == k); @ loop assigns i; @ loop assigns f[..]; @ loop variant N - i; @*/ for (int i = 0; i < N; i++) if (f[a[i]-1]) return a[i]; else f[a[i]-1] = true; return 0; }
34
/*@ requires a >= -2147483648 && a <= 2147483647; requires b >= -2147483648 && b <= 2147483647; ensures \result == a; */ int trans(int a, int b){ int c = a; b = c; return b; }
3
#include<stdio.h> struct scorecard{ int total_runs; int wickets; int total_overs; int over_complete; int target_score; }; /*@ requires 0<=runs<1000 && 0<=wic<=10 && 0<=comp<=20; ensures a->total_runs==\old(a->total_runs)+runs; ensures a->wickets==\old(a->wickets)+wic; ensures a->over_complete==\old(a->over_complete)+comp; */ void update_scorecard(struct scorecard *a,int runs, int wic,int comp){ a->total_runs+=runs; a->wickets+=wic; a->over_complete+=comp; }
3
/* run.config_qualif DONTRUN: [PB] temporary removed since a difference has to be validated. */ /* run.config_qualif OPT: -wp-par 1 -load-script tests/wp_plugin/combined.ml */ /* ZD : this should not be here such as it cannot be tested by all frama-c developer */ /*@ axiomatic A { @ predicate P(int x); @ }*/ /*@ ensures P(\result); @ assigns \nothing; */ int f(int i); /*@ assigns \nothing; */ int g(int j); void job(int *t, int A) { /*@ assert 50 <= A <= 100; */ /*@ loop invariant 0 <= i <= 50; @ loop invariant \forall integer k; 0 <= k < i ==> P(t[k]); @ loop assigns i,t[0..49]; @ */ for(int i = 0; i < 50; i++) t[i] = f(i); /*@ loop invariant A <= j <= 100; @ loop assigns j,t[A..99]; @ */ for(int j = A; j < 100; j++) t[j] = g(j); /*@ assert \forall integer k; 0 <= k < 50 ==> P(t[k]); */ } int T[100]; void main(void) { job(T, 50); // job(T, 48); }
3
/*@ requires \valid(p); requires \valid(q); assigns *p; assigns *q; ensures *p == \old(*q); ensures *q == \old(*p); */ void swap(int* p, int* q){ int tmp = *p; *p=*q; *q=tmp; return; }
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/*@ @ requires 0 <= n <= 1000; @ ensures 2 * \result == n * (n + 1); @ assigns \nothing; */ int sum_n(int n) { int res = 0; /*@ @ loop invariant 0 <= i <= n + 1; @ loop invariant 2 * res == i * (i - 1); @ loop variant n - i + 1; */ for (int i = 0; i <= n; ++i) { res += i; } return res; }
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typedef struct vector { int* addr; unsigned int sz; unsigned int cap; } vector; /*@ predicate invariant{L}(vector* v) = v->sz <= v->cap && \valid(v->addr + (0..v->cap-1)) && \separated(v, v->addr + (0..v->cap-1)); predicate full{L}(vector* v) = (v->sz == v->cap); */ /*@ requires \valid(v); requires invariant(v); assigns v->sz; assigns v->addr[v->sz]; behavior enough_space: assumes !full{Pre}(v); assigns v->sz; assigns v->addr[v->sz]; ensures \result == 1; ensures v->sz == \old(v->sz) + 1; ensures v->addr[\old(v->sz)] == x; ensures \forall integer i; 0 <= i < \old(v->sz) ==> v->addr[i] == \old(v->addr[i]); behavior no_space: assumes full{Pre}(v); assigns \nothing; ensures \result == 0; complete behaviors; disjoint behaviors; */ int push_back(vector* v, int x) { if (v->sz < v->cap) { v->addr[v->sz] = x; v->sz++; return 1; } else { return 0; } } /*@ requires \valid(v); requires invariant(v); requires v->sz + 1 < v->cap; assigns v->sz; assigns v->addr[v->sz]; assigns v->addr[v->sz + 1]; ensures v->sz == \old(v->sz) + 2; ensures v->addr[\old(v->sz)] == x; ensures v->addr[\old(v->sz) + 1] == x; ensures \forall integer i; 0 <= i < \old(v->sz) ==> v->addr[i] == \old(v->addr[i]); */ void push_back_twice(vector* v, int x) { push_back(v, x); //@ assert !full(v); push_back(v, x); }
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//find the max element of array /*@ requires n>0; requires \valid_read(arr+(0..n-1)); ensures \forall integer res; 0<=res<n ==> \result >= arr[res]; */ int checkPrime(int arr[], int n) { int max = arr[0]; /*@ loop invariant \forall integer k; 0<=k<i ==> max>=arr[k]; loop invariant 1<=i<=n; loop assigns i, max; loop variant n-i; */ for (int i = 1; i < n; i++) { if (max < arr[i]) { max = arr[i]; } } return max; }
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/*@ requires \valid(a); requires \valid(b); assigns *a; assigns *b; ensures *a == \old(*b); ensures *b == \old(*a); */ void swap(int *a, int *b); /*@ requires \valid(a); requires \valid(b); assigns *a, *b; ensures *a <= *b; behavior ret: assumes *a <= *b; ensures *a == \old(*a); ensures *b == \old(*b); behavior swap: assumes *a > *b; ensures *a == \old(*b); ensures *b == \old(*a); complete behaviors; disjoint behaviors; */ void max_ptr(int *a, int *b) { if (*a <= *b) { return; } else { swap(a, b); } }
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typedef int assert; assert behavior = 0; /*@ logic assert foo(assert x) = x; */ /*@ requires behavior >= 0; assigns behavior \from behavior; ensures behavior >= 0; */ int main () { behavior++; return 0; } /*@ type List<A> = Nil | Cons(A,List<A>); */ /*@ inductive model{L}(List<integer> root, List<integer>logic_list) { case nil{L}: model(Nil,Nil); case cons{L}: \forall List<integer> l1,List<integer>ll1; model{L}(l1,ll1) ==> model(Cons(0,l1),Cons(0,ll1)); } */
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#include <limits.h> /*@ requires ((((((((0<x0) && (x0<100)) && (0<x1)) && (x1<100)) && (0<=x2)) && (0<=x3)) && (x2<x0)) && (x3<x1)); assigns \nothing; ensures ((0<=\result) && (\result<(x0*x1))); */ int index(int x0, int x1, int x2, int x3) { int x5 = x2 * x1; int x6 = x5 + x3; return x6; } /*@ predicate inv_matrix_Boolean(int * x36, int x37, int x38) = (((((x37<100) && (x38<100)) && (0<x37)) && (0<x38)) && (((x37*x38)>0) && \valid(x36+(0..(x37*x38)-1))));*/ /*@ requires (((inv_matrix_Boolean(x79,x80,x81) && inv_matrix_Boolean(x82,x83,x84)) && inv_matrix_Boolean(x85,x86,x87)) && (((x81==x83) && (x80==x86)) && (x84==x87))); ensures ((inv_matrix_Boolean(x79,x80,x81) && inv_matrix_Boolean(x82,x83,x84)) && inv_matrix_Boolean(x85,x86,x87)); */ void mult(int * x79, int x80, int x81, int * x82, int x83, int x84, int * x85, int x86, int x87) { /*@ loop invariant 0<=x92<=x80; loop assigns x92, x85[(0..(x86*x87)-1)]; loop variant x80-x92; */ for(int x92=0; x92 < x80; x92++) { /*@ loop invariant 0<=x94<=x84; loop assigns x94, x85[(0..(x86*x87)-1)]; loop variant x84-x94; */ for(int x94=0; x94 < x84; x94++) { int x95 = index(x86,x87,x92,x94); x85[x95] = 0/*false*/; /*@ loop invariant 0<=x98<=x81; loop assigns x98, x85[(0..(x86*x87)-1)]; loop variant x81-x98; */ for(int x98=0; x98 < x81; x98++) { int x99 = x85[x95]; int x100 = index(x80,x81,x92,x98); int x101 = x79[x100]; int x104; if (x101) { int x102 = index(x83,x84,x98,x94); int x103 = x82[x102]; x104 = x103; } else { x104 = 0/*false*/; } int x105 = x99 || x104; x85[x95] = x105; } } } }
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# pragma SeparationPolicy(none) /*@ requires \valid(p); requires \valid(q); assigns *p; assigns *q; ensures *p == \old(*q); ensures *q == \old(*p); */ void swap(int* p, int* q) { int const save = *p; *p = *q; *q = save; } int main () { int p[2] = { 0,1}; int *q = (int *)((char*)q+1); swap(p,q); }
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#include <limits.h> #include <string.h> /*@ requires ((strlen(x0)>=0) && \valid(x0+(0..strlen(x0)))); assigns \nothing; ensures ((\result==-1) || ((0<=\result) && (\result<=9))); */ int p(char * x0) { int x8 = -1; int x9 = 1/*true*/; char x10 = '\0'; char *x11 = 0/*null*/; char x2 = x0[0]; int x3 = x2 == '\0'; if (x3) { x11 = x0; } else { int x4 = x2 >= '0'; int x6; if (x4) { int x5 = x2 <= '9'; x6 = x5; } else { x6 = 0/*false*/; } if (x6) { x9 = 0/*false*/; x10 = x2; char *x7 = x0+1; x11 = x7; } else { x11 = x0; } } int x23 = x9; if (x23) { char *x24 = x11; } else { char x26 = x10; char *x28 = x11; char x27 = x26 - '0'; x8 = x27; } int x32 = x8; return x32; }
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/* **************************************************************************** MATRICE SYMÉTRIQUE L'énoncé est introduit sous la forme de commentaires C. Les différents morceaux de programme et de spécification à considérer sont mentionnés en programmation littéraire : https://en.wikipedia.org/wiki/Literate_programming ************************************************************************* */ /* --------------------------------------------------------------------------- Petits rappels de mathématiques élémentaires à toutes fins utiles : - Une matrice carrée de taille N (N, entier naturel) est une matrice possédant N lignes et N colonnes. - Une matrice carrée A est dite symétrique si et seulement si A_{ij} = A_{ji} pour toute ligne [i] et colonne [j]. ------------------------------------------------------------------------- */ #include <stdbool.h> /* --------------------------------------------------------------------------- La fonction [is_symmetric] ci-dessous retourne [true] si et seulement si [matrix] est une matrice symétrique de taille [len]. Elle retourne [false] sinon. Question 1 : spécifier cette fonction en utilisant des comportements ACSL. Question 2 : prouver cette fonction, y compris sa terminaison et l'absence d'erreurs à l'exécution. ------------------------------------------------------------------------- */ /*@ requires \valid(matrix[0..len-1]+(0..len-1)); @ requires \valid(matrix+(0..len-1)); @ requires len >= 0; @ assigns \nothing; @ behavior symm: @ assumes \forall integer i,j; 0 <= i < len ==> 0 <= j < len ==> matrix[i][j] == matrix[j][i]; @ ensures \result == true; @ behavior nosymm: @ assumes \exists integer i,j; 0 <= i < len && 0 <= j < len && matrix[i][j] != matrix[j][i]; @ ensures \result == false; @ complete behaviors; @ disjoint behaviors; @ */ _Bool is_symmetric(int **matrix, int len) { /*@loop invariant 0 <= i <= len; @loop invariant \forall integer k, l; 0 <= k < i ==> 0 <= l < k ==> matrix[k][l] == matrix[l][k]; @loop assigns i; @loop variant len - i; @ */ for (int i = 0; i < len; i++) /*@loop invariant 0 <= j <= i; @loop invariant \forall integer k; 0 <= k < j ==> matrix[i][k] == matrix[k][i]; @loop assigns j; @loop variant i - j; @ */ for (int j = 0; j < i; j++) if (matrix[i][j] != matrix[j][i]) return false; return true; }
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/*@ assigns \nothing; ensures \result == \max(a, b) - \min(a, b); */ unsigned distance(unsigned a, unsigned b) { return (a > b) ? (a - b) : (b - a); }
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#include <stdbool.h> /*@ requires N > 0; @ requires \valid(a+(0..N-1)); @ requires \forall integer i; @ 0 <= i < N ==> -1000000000 <= a[i] <= 1000000000; @ ensures \result <==> (\exists integer i, j; @ 0 <= i < j < N && a[i] + a[j] == X); @*/ bool sumx (int N, int a[], int X) { int i, j; /*@ loop invariant 0 <= i < N; @ loop invariant \forall integer ii, jj; @ 0 <= ii < jj < N && ii < i ==> a[ii] + a[jj] != X; @ loop assigns i, j; @ loop variant N-i-2; @*/ for (i=0; i<N-1; i++) /*@ loop invariant i+1 <= j <= N; @ loop invariant \forall integer ii, jj; @ 0 <= ii < jj < N && ii < i ==> a[ii] + a[jj] != X; @ loop invariant \forall integer jj; @ 0 <= i < jj < j ==> a[i] + a[jj] != X; @ loop assigns j; @ loop variant N-j; @*/ for (j=i+1; j<N; j++) if (a[i] + a[j] == X) return true; return false; }
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/*@ requires 0 <= N <= 1000000000; assigns \nothing; ensures \result * \result <= N ; ensures N < (\result+1) * (\result+1); */ int root(int N){ int R = 0; /*@ loop invariant 0 <= R * R <= N; loop assigns R; loop variant N-R; */ while(((R+1)*(R+1)) <= N) { R = R + 1; } return R; }
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#include <string.h> /*@ requires strlen(a)>=0 && \valid(a+(0..strlen(a))); assigns \nothing; ensures 0<=\result || \result==-1; */ int my_atoi(char* a) { int m = INT_MAX/10 - 10; int r = 0; char* s = a; /*@ loop invariant strlen(s)>=0 && \valid(s+(0..strlen(s))); loop invariant 0 <= r; loop assigns r, s; loop variant strlen(s); */ while ('0' <= *s && *s <= '9') { if (r > m) return -1; r = 10*r + (*s - '0'); s++; } return r; }
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/*@ logic integer \fact(integer n) = (n <= 0) ? 1 : n * \fact(n-1); */ /*@ requires n >= 0 && n <= 10; ensures \result == \fact(n); assigns \nothing; */ int factorial(int n) { int i = 1; int f = 1; /*@ loop invariant 1 <= i <= n+1; loop invariant f == \fact(i-1); loop assigns f, i; loop variant n-i+1; */ while (i<=n) { f = f * i; i = i + 1; } return f; } /*@ assigns \nothing; */ int main(void) { int n = 5; int ret = factorial(n); return 0; }
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typedef struct _singly_list { int elt; struct _singly_list* next; } singly_list_t; /*@ @ type list<A> = Nul | Cons(A, list<A>); @ @ */ /*@ @ inductive wf_singly_list{L}(singly_list_t* lst){ @ case empty: \forall singly_list_t* lst; lst == \null ==> wf_singly_list(lst); @ case non_empty: \forall singly_list_t* lst; lst != \null ==> \valid(lst) ==> wf_singly_list(lst->next) ==> wf_singly_list(lst); @ } @ @ axiomatic wf_singly_list { @ axiom wf_singly_list_inversion: \forall singly_list_t* lst; wf_singly_list(lst) ==> @ lst == \null || @ (lst != \null && \valid(lst) && wf_singly_list(lst->next)); @ } @ @ */ /*@ @ inductive singly_list_length{L}(singly_list_t* lst, integer sz){ @ case empty: \forall singly_list_t* lst; lst == \null ==> singly_list_length(lst, 0); @ case non_empty: \forall singly_list_t* lst; \forall integer sz; lst != \null ==> \valid(lst) ==> singly_list_length(lst->next, sz) ==> singly_list_length(lst, sz+1); @ } @ @ axiomatic singly_list_length { @ axiom singly_list_length_inversion: \forall singly_list_t* lst; \forall integer sz; singly_list_length(lst, sz) ==> @ (lst == \null && sz == 0) || @ (\exists integer sz2; lst != \null && \valid(lst) && singly_list_length(lst->next, sz2) && sz == sz2+1); @ } @ */ /*@ @ inductive reachable{L}(singly_list_t *lst1, singly_list_t *lst2, integer n){ @ case reachable1: \forall singly_list_t *lst; reachable(lst, lst, 0); @ case reachable2: \forall singly_list_t *lst1, *lst2; \forall integer n1, n2; lst1 != \null ==> \valid(lst1) ==> n2 == n1 + 1 ==> reachable(lst1->next, lst2, n1) ==> reachable(lst1, lst2, n2); @ } @ @ @ */ /*@ @ axiomatic reachable { @ axiom reachable_inversion: \forall singly_list_t *lst1, *lst2; \forall integer n; reachable(lst1, lst2, n) ==> @ (lst1 == lst2 && n == 0) || (n > 0 && lst1 != \null && \valid(lst1) && reachable(lst1->next, lst2, n - 1)); @ axiom reachable_trans: \forall singly_list_t *lst1, *lst2, *lst3; \forall integer n1, n2, n3; n3 == n1 + n2 ==> reachable(lst1, lst2, n1) ==> reachable(lst2, lst3, n2) ==> reachable(lst1, lst3, n3); @ // fora now as axioms ... @ // axiom reachable_lhs_next: \forall singly_list_t *lst; lst != \null && \valid(lst) ==> reachable(lst, lst->next, 1); @ axiom reachable_rhs_next: \forall singly_list_t *lst1, *lst2; \forall integer n; reachable(lst1, lst2, n) && lst2 != \null && \valid(lst2) ==> reachable(lst1, lst2->next, n + 1); @ } @ @ @ @ predicate circular_singly_list{L}(singly_list_t *lst) = \exists singly_list_t* lst2; \exists integer n; @ reachable(lst, lst2, n) && (\exists integer m; m >0 && reachable (lst2, lst2, m)); @ @ axiomatic circular_singly_list { @ // this should be a lemma ... @ axiom null_reachable_non_circular: \forall singly_list_t *lst; \forall integer n; reachable(lst, \null, n) ==> !circular_singly_list(lst); @ } @ @ */ /*@ // algorithm for detecting circular list @ requires wf_singly_list(lst); @ ensures wf_singly_list(lst); @ assigns \nothing; @ ensures \result == 0; @*/ int is_circular_singly_list(singly_list_t* lst) { return 0; }
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/* Generated by Frama-C */ int global_i; int *global_i_ptr = & global_i; int global_i = 0; /*@ assigns \nothing; */ void loop(void) { return; } /*@ assigns \nothing; */ void __gen_e_acsl_loop(void) { loop(); return; } /*@ assigns global_i, global_i_ptr; */ int main(void) { int __retres; /* Initialize global variables */ global_i = 0; global_i_ptr = &global_i; __gen_e_acsl_loop(); __retres = 0; return __retres; }
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#include<limits.h> /*@ requires x >= 1; requires y >= 1; requires z>= 1; requires x<=INT_MAX && y<=INT_MAX && z<=INT_MAX; requires x+y<=INT_MAX && y+z<=INT_MAX && z+x<=INT_MAX; ensures (x+y <= z || y+z <=x || x+z <=y) ==> \result == 0; ensures x+y > z && y+z >x && x+z >y && x == y && y == z ==> \result==1; ensures x+y > z && y+z >x && x+z >y && (x != y || y != z) ==> \result==0; assigns \nothing; */ int triangle(int x,int y,int z) { if(x+y > z && y+z >x && x+z >y) { if(x == y && y == z){ return 1; } else if(x == y || y == z || x==z){ return 0; } else if((x!=y)&&(y!=z)&&(z!=x)) { return 0; } } return 0; } int main() { int t = triangle(4,4,4); return 0; }
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/*@ axiomatic ellipsoids_proof_tactics { @ type ellipsoids_tactics = Intuition | Tactic2; @ predicate use_strategy (ellipsoids_tactics t); @ } */ /*@ requires x < 0 && x > -1073741824; @ ensures \result == 2 * (x + 1); @ assigns \nothing; */ int plus_one (int x) { int y,z; { /*@ assert x + 1 <= 1073741823; */ y = x + 1; } { /*@ assert 2 * y <= 2147483647; */ z = 2 * y; } return z; }
10
/*@ @ requires n > 0; @ requires \valid_read(a+(0..n - 1)); @ requires \valid_read(b+(0..n - 1)); @ requires \valid(c+(0..n - 1)); @ requires \separated(a+(0..n-1), b+(0..n-1), c+(0..n-1)); @ requires \forall integer i; 0 <= i < n ==> -10000 <= a[i] <= 10000; @ requires \forall integer i; 0 <= i < n ==> -10000 <= b[i] <= 10000; @ ensures \forall integer i; 0 <= i < n ==> c[i] == a[i] + b[i]; @ assigns c[0..n-1]; */ void sum_array(int a[], int b[], int c[], int n) { /*@ @ loop invariant 0 <= i <= n; @ loop invariant \valid_read(a+(0..n - 1)); @ loop invariant \valid_read(b+(0..n - 1)); @ loop invariant \valid(c+(0..n - 1)); @ loop invariant \forall integer j; 0 <= j < i ==> c[j] == a[j] + b[j]; @ loop assigns i, c[0..n-1]; @ loop variant n - i; */ for (int i = 0; i < n; ++i) { c[i] = a[i] + b[i]; } }
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/*@ requires \valid_read(p); ensures \result == *p; */ int foo(int* p) { return *p; }
4
/*@ requires \valid_read(p) && \valid_read(q); requires -10000000<*p<10000000 && -10000000<*q<10000000; ensures \result==*p+*q; assigns \nothing; */ int add(int*p,int*q){ return*p + *q ; } /*@ assigns \nothing; */ int main(){ int a =24,b =42,x ; x = add(&a, &b) ; x = add(&a, &a) ; }
20
/*@ predicate valid_subseq{L}(int *x, integer left, integer right) = @ left < right ==> \forall integer i, j; left <= i < right && left <= j < right ==> x[i] == x[j]; */ /*@ requires 1 <= N <= 1000000; @ requires \valid(x + (0..N-1)); @ ensures 1 <= \result <= N; @ ensures \exists integer k; 0 <= k < N && valid_subseq(x, k, k + \result); @ assigns \nothing; */ int countSameConsecutive(int N, int x[]) { int best = 0, i = 0; /*@ loop invariant 0 <= i <= N; @ loop invariant i == 0 ==> best == 0; @ loop invariant i > 0 ==> 1 <= best <= i; @ loop invariant i > 0 ==> \exists integer k; 0 <= k < i && valid_subseq(x, k, k + best); @ loop assigns i, best; @ loop variant N - i; */ while (i < N) { int j = i+1; /*@ loop invariant i < j <= N; @ loop invariant valid_subseq(x, i, j); @ loop assigns j; @ loop variant N - j; */ while (j < N && x[j] == x[i]) ++j; /*@ assert (j < N ==> (x[j] != x[i] && x[j] != x[j - 1])) || j == N;*/ /*@ assert i == 0 && j == N ==> valid_subseq(x, 0, N);*/ if (j-i > best) best = j-i; /*@ assert j - i <= best;*/ i = j; } /*@ assert best <= N;*/ return best; }
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/*@ requires \valid(t+(0..n-1)) && n>0; ensures (\forall integer i; 0<=i<n ==> t[i] == 0) ==> \result == 1; ensures (\exists integer i; 0<=i<n && t[i] != 0) ==> \result == 0; */ int all_zeros(int t[], int n){ /*@ loop invariant 0<=i<=n; loop invariant \forall integer j; 0 <= j < i ==> t[j] == 0; loop assigns i; loop variant n-i; */ for(int i=0;i<n;i++){ if(t[i] != 0) return 0; } return 1; }
13
/*@ requires x >= 0; ensures \result == x; assigns \nothing; */ int foo(int x) { return x; }
4
/*@ requires n <= 2147483646; ensures \result == \old(n) + 1 ; assigns \nothing; */ int incr(int n) { return n+1; };
5
//@ predicate null(char *x) = x == 0; //@ predicate eq(char *x, char *y) = x == y; //@predicate my_null(char *x) = x == (void*)0; void f(char *x) { x = 0; //@ assert x == (void*)0; //@ assert my_null(x); //@ assert null(x); //@ assert eq(x,0); } //@ ensures \result == \true; int g() { return 1; } /*@ predicate foo (integer x) = x != 0; */ /*@ ensures foo(1); */ int h() { return 1; }
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