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. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)assert.3 8.1 (Berkeley) 6/9/93 29.\" $FreeBSD: src/share/man/man3/assert.3,v 1.15 2002/12/04 18:57:46 ru Exp $ 30.\" $DragonFly: src/share/man/man3/assert.3,v 1.2 2003/06/17 04:36:58 dillon Exp $ 31.\" 32.Dd January 26, 1999 33.Dt ASSERT 3 34.Os 35.Sh NAME 36.Nm assert 37.Nd expression verification macro 38.Sh SYNOPSIS 39.In assert.h 40.Fn assert expression 41.Sh DESCRIPTION 42The 43.Fn assert 44macro tests the given 45.Ar expression 46and if it is false, 47the calling process is terminated. 48A 49diagnostic message is written to 50.Dv stderr 51and the function 52.Xr abort 3 53is called, effectively terminating the program. 54.Pp 55If 56.Ar expression 57is true, 58the 59.Fn assert 60macro does nothing. 61.Pp 62The 63.Fn assert 64macro 65may be removed at compile time by defining 66.Dv NDEBUG 67as a macro 68(e.g., by using the 69.Xr cc 1 70option 71.Fl D Ns Dv NDEBUG ) . 72.Sh EXAMPLES 73The assertion: 74.Pp 75.Dl "assert(1 == 0);" 76.Pp 77generates a diagnostic message similar to the following: 78.Pp 79.Dl "Assertion failed: (1 == 0), function main, file assertion.c, line 100." 80.Sh SEE ALSO 81.Xr abort 3 82.Sh STANDARDS 83The 84.Fn assert 85macro conforms to 86.St -isoC-99 . 87.Sh HISTORY 88An 89.Nm 90macro appeared in 91.At v6 . 92