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In this example, the function pointer fp is used to refer to the function strchr(), which is defined elsewhere. However, fp is defined without the appropriate parameter list, and the function prototype for strchr() is not visible to this program. As a result there is no type checking performed on the call to fp(12,2);.

#include <stdio.h>
extern char *strchr();#include <string.h>

char *(*fp) ();

int main(void) {
  char *c;
  fp = strchr;
  c = fp(12,2);
  printf("%s\n",c);

}

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Compliant Solution: (function pointers)

Properly declaring fp so it is compatible with strchr() corrects this example.

#include <string.h>

char *(*fp) (cjarconst char *,int);

int main(void) {
  char *c;
  fp = strchr;
  c = fp("Hello",'H');
  printf("%s\n",c);

}

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