1.\" $OpenBSD: assert.3,v 1.5 2000/10/26 00:37:03 aaron 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. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)assert.3 8.1 (Berkeley) 6/9/93 36.\" 37.Dd June 9, 1993 38.Dt ASSERT 3 39.Os 40.Sh NAME 41.Nm assert 42.Nd expression verification macro 43.Sh SYNOPSIS 44.Fd #include <assert.h> 45.Fn assert expression 46.Sh DESCRIPTION 47The 48.Fn assert 49macro tests the given 50.Ar expression 51and if it is false, the calling process is terminated. 52A diagnostic message is written to 53.Em stderr 54and the 55.Xr abort 3 56function is called, effectively terminating the program. 57.Pp 58If 59.Ar expression 60is true, the 61.Fn assert 62macro does nothing. 63.Pp 64The 65.Fn assert 66macro may be removed at compile time with the 67.Xr cc 1 68option 69.Fl DNDEBUG . 70.Sh DIAGNOSTICS 71The following diagnostic message is written to 72.Em stderr 73if 74.Ar expression 75is false: 76.Bd -literal -offset indent 77"assertion \e"%s\e" failed: file \e"%s\e", line %d\en", \e 78 "expression", __FILE__, __LINE__); 79.Ed 80.Sh SEE ALSO 81.Xr cc 1 , 82.Xr abort 3 83.Sh STANDARDS 84The 85.Fn assert 86macro conforms to 87.St -ansiC . 88.Sh HISTORY 89An 90.Fn assert 91macro appeared in 92.At v6 . 93