Used for implementing run-time diagnostics in programs.

    Format

      #include  <assert.h>

      void assert  (int expression);

1  –  Argument

 expression

    An expression that has an int type.

2  –  Description

    When assert is executed, if expression is false (that is, it
    evaluates to 0), assert writes information about the particular
    call that failed (including the text of the argument, the name of
    the source file, and the source line number; the latter two are,
    respectively, the values of the preprocessing macros __FILE__
    and __LINE__)  to the standard error file in an implementation-
    defined format. Then, it calls the abort function.

    The assert function writes a message in the following form:

    Assertion failed:  expression, file aaa, line nnn

    If expression is true (that is, it evaluates to nonzero) or if
    the signal SIGABRT is being ignored, assert returns no value.

                                   NOTE

       If a null character ('\0') is part of the expression being
       asserted, then only the text up to and including the null
       character is printed, since the null character effectively
       terminates the string being output.

    Compiling with the CC command qualifier /DEFINE=NDEBUG or with
    the preprocessor directive #define NDEBUG ahead of the #include
    assert statement causes the assert function to have no effect.

3  –  Example

        #include <stdio.h>
        #include <assert.h>

        main()
        {
            printf("Only this and the assert\n");
            assert(1 == 2);     /* expression is FALSE */

    /* abort should be called so the printf will not happen. */

            printf("FAIL abort did not execute");
        }