static_assert

#define static_assert _Static_assert

This convenience macro expands to the keyword _Static_assert.

Example

#include <assert.h>
 
int main(void)
{
    static_assert(2 + 2 == 4, "2+2 isn't 4");   // well-formed
 
    static_assert(sizeof(int) < sizeof(char),   // compile-time error
                  "this program requires that int is less than char");
}

Notes

Since C23, static_assert is itself a keyword, which may also be a predefined macro, so <assert.h> no longer provides it.

References

• C17 standard (ISO/IEC 9899:2018):
• 7.2/3 Diagnostics <assert.h> (p: 135)
• C11 standard (ISO/IEC 9899:2011):
• 7.2/3 Diagnostics <assert.h> (p: 186)

See also