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assert.3

ASSERT

Section: Linux Programmer's Manual (3)
Updated: 2002-08-25
Index Return to Main Contents
 

NAME

assert - abort the program if assertion is false  

SYNOPSIS

#include <assert.h>

void assert(scalar expression);
 

DESCRIPTION

If the macro NDEBUG was defined at the moment <assert.h> was last included, the macro assert() generates no code, and hence does nothing at all. Otherwise, the macro assert() prints an error message to standard error and terminates the program by calling abort(3) if expression is false (i.e., compares equal to zero).

The purpose of this macro is to help the programmer find bugs in his program. The message "assertion failed in file foo.c, function do_bar(), line 1287" is of no help at all to a user.  

RETURN VALUE

No value is returned.  

CONFORMING TO

POSIX.1-2001, C89, C99. In C89, expression is required to be of type int and undefined behavior results if it is not, but in C99 it may have any scalar type.  

BUGS

assert() is implemented as a macro; if the expression tested has side-effects, program behavior will be different depending on whether NDEBUG is defined. This may create Heisenbugs which go away when debugging is turned on.  

SEE ALSO

abort(3), assert_perror(3), exit(3)  

COLOPHON

This page is part of release 3.21 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
CONFORMING TO
BUGS
SEE ALSO
COLOPHON

 

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