1.\" $OpenBSD: assert.3,v 1.8 2013/06/05 03:42:03 tedu Exp $ 2.\" $NetBSD: assert.3,v 1.5 1994/11/30 15:24:30 jtc Exp $ 3.\" 4.\" Copyright (c) 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)assert.3 8.1 (Berkeley) 6/9/93 32.\" 33.Dd $Mdocdate: June 5 2013 $ 34.Dt ASSERT 3 35.Os 36.Sh NAME 37.Nm assert 38.Nd expression verification macro 39.Sh SYNOPSIS 40.In assert.h 41.Fn assert expression 42.Sh DESCRIPTION 43The 44.Fn assert 45macro tests the given 46.Ar expression 47and if it is false, the calling process is terminated. 48A diagnostic message is written to 49.Em stderr 50and the 51.Xr abort 3 52function is called, effectively terminating the program. 53.Pp 54If 55.Ar expression 56is true, the 57.Fn assert 58macro does nothing. 59.Pp 60The 61.Fn assert 62macro may be removed at compile time with the 63.Xr cc 1 64option 65.Fl DNDEBUG . 66.Sh DIAGNOSTICS 67The following diagnostic message is written to 68.Em stderr 69if 70.Ar expression 71is false: 72.Bd -literal -offset indent 73"assertion \e"%s\e" failed: file \e"%s\e", line %d\en", \e 74 "expression", __FILE__, __LINE__); 75.Ed 76.Sh SEE ALSO 77.Xr cc 1 , 78.Xr abort 3 79.Sh STANDARDS 80The 81.Fn assert 82macro conforms to 83.St -ansiC . 84.Sh HISTORY 85An 86.Fn assert 87macro appeared in 88.At v6 . 89