Synopsis

Use valid format strings.

Enabled by default

Yes

Severity/Certainty

High/Low

Full description

The formatted output functions (fprintf() and related functions) convert, format, and print their arguments under control of a format string. The C standard outlines what format specifiers are valid in a format string. This check will find cases where the types of the arguments to a format string function do not match the format string specifiers.

Coding standards

Code examples

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

#include <stdio.h>

void func(void) {
  const char *error_msg = "Resource not available to user.";
  int error_type = 3;
  /* ... */
  printf("Error (type %s): %d\n", error_type, error_msg);
  /* ... */
}

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

#include <stdio.h>

void func(void) {
  const char *error_msg = "Resource not available to user.";
  int error_type = 3;
  /* ... */
  printf("Error (type %d): %s\n", error_type, error_msg);

  /* ... */
}