Standard C Library WITH Example Codes

1. <assert.h> Diagnostics

The assert macro is used to add diagnostics to programs:

void assert(int expression)

If expression is zero (false) 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 (in <stdlib.h>) 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.

EXAMPLE CODES

1. assert.h

l assert.c

#include <stdio.h>
#include <assert.h>void out(int *p) {
    assert(p != NULL);
    printf("%d\n", *p);
}void main() {
    int n = 10;
    out(&n);
    out(NULL);
}

> cl assert.c && assert

Assertion failed: p != NULL, file assert.c, line 4

This application has requested the Runtime to terminate it in an unusual way.

Please contact the application's support team for more information.

> cl -D "NDEBUG" assert.c && assert

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