Chapter-4/4-4/polishcalc.c
/* show_top:  prints the top element of the stack without popping */
prints the top element of the stack without popping
prints the top element of the stack without popping
void show_top(void) {
  if (sp > 0)
    printf("top element of stack: %g\n", val[sp - 1]);
  else
    printf("error: stack empty\n");
}
void show_top ( void ) { if ( sp > 0 ) printf ( " \n " , val [ sp - 1 ] ) ; else printf ( " \n " ) ; }
show_top:  prints the top element of the stack without popping
show_top : prints the top element of the stack without popping