From WikiChip
static_assert macro - <assert.h> - C
< c‎ | assert.h

The static_assert macro, which is part of <assert.h>, is a convenient object-like macro name that expands to the _Static_assert keyword.


#include <assert.h>
#define static_assert _Static_assert


The static_assert object-like macro expands to the _Static_assert, a keyword added in C11 to provide compile-time assertion.


#include <assert.h>

static_assert(sizeof(int) == 4, "Code relies on int being exactly 4 bytes");

int main(void)
    return 0;

On a machine where sizeof (int) is not 4, a constraint violation occurs. On such implementations, a diagnostic message is printed similar to the one below:

example.c:3:1: error: static assertion failed "Code relies on int being exactly 4 bytes"