TCPL/B.06_Diagnostics:_<assert.h>

The assert macro is used to add diagnostics to programs:

void assert(int expression)

If expression is zero when

assert(expression)

is executed, the assert macro will print on stderr a message, such as

Assertion failed: expression, file filename, line nnn

It then calls abort to terminate execution. The source filename and line number come from the preprocessor macros __FILE__ and __LINE__.

If NDEBUG is defined at the time <assert.h> is included, the assert macro is ignored.