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ASSERT(3)              FreeBSD Library Functions Manual              ASSERT(3)

NAME
     assert - expression verification macro

SYNOPSIS
     #include <assert.h>

     assert(expression);

DESCRIPTION
     The assert() macro tests the given expression and if it is false, the
     calling process is terminated.  A diagnostic message is written to stderr
     and the function abort(3) is called, effectively terminating the program.

     If expression is true, the assert() macro does nothing.

     The assert() macro may be removed at compile time by defining NDEBUG as a
     macro (e.g., by using the cc(1) option -DNDEBUG).

EXAMPLES
     The assertion:

           assert(1 == 0);

     generates a diagnostic message similar to the following:

           Assertion failed: (1 == 0), function main, file assertion.c, line
           100.

SEE ALSO
     abort(3)

STANDARDS
     The assert() macro conforms to ISO/IEC 9899:1999 (``ISO C99'').

HISTORY
     An assert macro appeared in Version 6 AT&T UNIX.

FreeBSD 11.1-RELEASE-p4        January 26, 1999        FreeBSD 11.1-RELEASE-p4
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