assert.h

Macros

assert(condition)

Expands to a void expression
If the expression evaluates to false (0), the macro writes diagnostic information to the standard error stream and calls the abort function.
If the NDEBUG macro is define before the inclusion of the assert.h header, the assert macro does nothing and the build is assumed to be a release.
No value is returned.

static_assert

Expands to _Static_assert
Macro for the keyword.