freebsd-dev/share/man/man3/assert.3
Mike Barcroft cb5f460523 Only provide function information in compile environments that support
the C99 variable __func__ and never for C++.  Provide a more meaningful
example in the assert(3) manual.

Reviewed by:	asmodai, bde
2001-10-27 20:11:10 +00:00

97 lines
2.8 KiB
Groff

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.\" @(#)assert.3 8.1 (Berkeley) 6/9/93
.\" $FreeBSD$
.\"
.Dd January 26, 1999
.Dt ASSERT 3
.Os
.Sh NAME
.Nm assert
.Nd expression verification macro
.Sh SYNOPSIS
.In assert.h
.Fn assert expression
.Sh DESCRIPTION
The
.Fn assert
macro tests the given
.Ar expression
and if it is false,
the calling process is terminated.
A
diagnostic message is written to
.Em stderr
and the function
.Xr abort 3
is called, effectively terminating the program.
.Pp
If
.Ar expression
is true,
the
.Fn assert
macro does nothing.
.Pp
The
.Fn assert
macro
may be removed at compile time by defining
.Dv NDEBUG
as a macro
(e.g., by using the
.Xr cc 1
option
.Fl D Ns Dv NDEBUG ) .
.Sh EXAMPLES
The assertion:
.Bd -literal -offset indent
assert(1 == 0);
.Ed
.Pp
generates a diagnostic message similar to the following:
.Bd -literal -offset indent
assertion (1 == 0) failed: function main(), file assertion.c:100
.Ed
.Sh SEE ALSO
.Xr abort 3
.Sh STANDARDS
The
.Fn assert
macro conforms to
.St -isoC-99 .
.Sh HISTORY
An
.Nm
macro appeared in
.At v6 .