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Non-Compliant Code Example: (function pointers)

If a function pointer is set to refer to an incompatible function , invoking that function via the pointer may cause unexpected data to be taken from the process stack. As a result, unexpected data may be accessed by the called function \[[DCL35-C. Do not convert a function

 pointer to a function of an incompatible type]\].

In this example, the function pointer Setting fn_ptr is set to point refer to add() strchr(), which is defined elsewhere. However, because fn_ptr is declared with an empty parameter type list, the compiler will not generate a warning if the wrong type, or number of arguments are supplied to fn_ptr. This could result in an unexpected value being used as parameter z in function add()results.

int add(int x, int y, int z) {
   return x + y + z;
}
int main(int argc, extern char *argv[]) {
   strchr();

int (*fn_ptr) ();

int, intmain(void) ;{
   intchar res*c;
   fn_ptr = add;
   resc = fn_ptr(2"Hello", 3'H');  /* incorrect */
   /* ... */
   return 0;
}

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