title: use isdigit with first element in for loop
body: <p>i have code and when i read from file i want to check if first elements of the word is number if yes stop the program and this is part of my code for example <code>sum = x * 3 / 5</code>
  this is ok because the sum doesn’t contain number but  <code>2sum</code> here should the program stop</p>
  
  <pre><code>#include &lt;stdio.h&gt; 
  #include &lt;ctype.h&gt;
  #include &lt;string.h&gt;
  #include &lt;stdlib.h&gt;
   int charClass;
   char lexeme [100]; 
   char nextChar; 
   int lexLen;
   int token; 
   int nextToken; 
  FILE *in_fp, *fopen();
  void addChar(); 
  void getChar();
  void getNonBlank(); 
  int lex();
  
  #define LETTER 0 
  #define DIGIT 1 
  #define UNKNOWN 99
  #define INT_LIT 10
  #define IDENT 11 
  #define ASSIGN_OP 20 
  #define ADD_OP 21 
  #define SUB_OP 22 
  #define MULT_OP 23
   #define DIV_OP 24 
   #define LEFT_PAREN 25 
   #define RIGHT_PAREN 26
   #define EQUAL_OP 27
   #define greater_than_OP 28
    #define key_Word_OP 29
    int main() {
    if ((in_fp = fopen("/Users/Desktop/ff.txt", "r")) == NULL) 
   printf("ERROR - cannot open front.in \n"); 
  else {
  getChar(); 
  </code></pre>
  
  <p>my problem here in for loop it check all elements not just first elements<br>
  i do not know why for example  <code>sum = x * 3 / 5</code> the program it is stop after 3 it should complete </p>
  
  <pre><code>do { 
   for( size_t i=0; lexeme[i]; i++ ){
          if(isdigit(lexeme[0]) )  {
      printf("erreo ");
  
     exit(0);
          } else{
              }
        }
        lex(); 
  
  
  
        } while (nextToken != EOF ); 
        }
    }
  </code></pre>