.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved 
.TH "ASSERT" 3P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\" assert 
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.SH NAME
assert \- insert program diagnostics
.SH SYNOPSIS
.LP
\fB#include <assert.h>
.br
.sp
void assert(scalar\fP \fIexpression\fP\fB);
.br
\fP
.SH DESCRIPTION
.LP
The \fIassert\fP() macro shall insert diagnostics into programs; it
shall expand to a \fBvoid\fP expression. When it is
executed, if \fIexpression\fP (which shall have a \fBscalar\fP type)
is false (that is, compares equal to 0), \fIassert\fP()
shall write information about the particular call that failed on \fIstderr\fP
and shall call \fIabort\fP().
.LP
The information written about the call that failed shall include the
text of the argument, the name of the source file, the
source file line number, and the name of the enclosing function; the
latter are, respectively, the values of the preprocessing
macros __FILE__ and __LINE__ and of the identifier __func__.
.LP
Forcing a definition of the name NDEBUG, either from the compiler
command line or with the preprocessor control statement
\fB#define\fP NDEBUG ahead of the \fB#include\fP \fI<assert.h>\fP
statement, shall
stop assertions from being compiled into the program.
.SH RETURN VALUE
.LP
The \fIassert\fP() macro shall not return a value.
.SH ERRORS
.LP
No errors are defined.
.LP
\fIThe following sections are informative.\fP
.SH EXAMPLES
.LP
None.
.SH APPLICATION USAGE
.LP
None.
.SH RATIONALE
.LP
None.
.SH FUTURE DIRECTIONS
.LP
None.
.SH SEE ALSO
.LP
\fIabort\fP(), \fIstderr\fP, the Base Definitions volume of IEEE\ Std\ 1003.1-2001,
\fI<assert.h>\fP
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .