Error directive

Shows the given error message and renders the program ill-formed.


#error error_message


After encountering the #error directive, an implementation displays the diagnostic message error_message and renders the program ill-formed (the compilation stops).

error_message can consist of several words not necessarily in quotes.


#if __STDC__ != 1
#  error "Not a standard compliant compiler"
#include <stdio.h>
int main (void)
    printf("The compiler used conforms to the ISO C Standard !!");

Possible output:

The compiler used conforms to the ISO C Standard !!


  • C11 standard (ISO/IEC 9899:2011):
  • 6.10.5 Error directive (p: 174)
  • C99 standard (ISO/IEC 9899:1999):
  • 6.10.5 Error directive (p: 159)
  • C89/C90 standard (ISO/IEC 9899:1990):
  • 3.8.5 Error directive

See also