Synopsis

A variable is tested for equality with a string literal.

Enabled by default

Yes

Severity/Certainty

Low/High

Full description

A variable is tested for equality with a string literal. This compares the variable with the address of the literal, which is probably not the intended behavior. It is more likely that the intent is to compare the contents of strings at different addresses, for example with the strcmp() function.

Coding standards

Code examples

The following code example fails the check and will give a warning:

#include <stdio.h>

int main (void) {
  char *p = "String";

  if (p == "String") {
    printf("They're equal.\n");
  }

  return 0;
}

The following code example passes the check and will not give a warning about this issue:

#include <stdio.h>
#include <string.h>

int main (void) {
  char *p = "String";

  //OK - using string comparison function
  if (strcmp(p,"String") == 0) {
    printf("They're equal.\n");
  }

  return 0;
}