1.\" Copyright (c) 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)assert.3 8.1 (Berkeley) 6/9/93 33.\" $FreeBSD$ 34.\" 35.Dd January 26, 1999 36.Dt ASSERT 3 37.Os 38.Sh NAME 39.Nm assert 40.Nd expression verification macro 41.Sh SYNOPSIS 42.In assert.h 43.Fn assert expression 44.Sh DESCRIPTION 45The 46.Fn assert 47macro tests the given 48.Ar expression 49and if it is false, 50the calling process is terminated. 51A 52diagnostic message is written to 53.Em stderr 54and the function 55.Xr abort 3 56is called, effectively terminating the program. 57.Pp 58If 59.Ar expression 60is true, 61the 62.Fn assert 63macro does nothing. 64.Pp 65The 66.Fn assert 67macro 68may be removed at compile time by defining 69.Dv NDEBUG 70as a macro 71(e.g., by using the 72.Xr cc 1 73option 74.Fl D Ns Dv NDEBUG ) . 75.Sh EXAMPLES 76The assertion: 77.Pp 78.Dl "assert(1 == 0);" 79.Pp 80generates a diagnostic message similar to the following: 81.Pp 82.Dl "assertion (1 == 0) failed: function main(), file assertion.c:100" 83.Sh SEE ALSO 84.Xr abort 3 85.Sh STANDARDS 86The 87.Fn assert 88macro conforms to 89.St -isoC-99 . 90.Sh HISTORY 91An 92.Nm 93macro appeared in 94.At v6 . 95