ASSERT(3)                 OpenBSD Programmer's 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 abort(3) function is called, effectively terminating the program.

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

     The assert() macro may be removed at compile time with the cc(1) option
     -DNDEBUG.

DIAGNOSTICS
     The following diagnostic message is written to stderr if expression is
     false:

           "assertion \"%s\" failed: file \"%s\", line %d\n", \
                               "expression", __FILE__, __LINE__);

SEE ALSO
     cc(1),  abort(3)

STANDARDS
     The assert() macro conforms to ANSI X3.159-1989 (``ANSI C'').

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

OpenBSD 2.6                      June 9, 1993                                1