assert
Section: C Library Functions (3)
Updated: 202-0-08
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NAME
assert - abort the program if assertion is false
LIBRARY
Standard C library
(
libc,~
-lc)
SYNOPSIS
#include <assert.h>
void assert(bool expression);
DESCRIPTION
This macro can help programmers find bugs in their programs,
or handle exceptional cases
via a crash that will produce limited debugging output.
If
expression
is false (i.e., compares equal to zero),
assert()
prints an error message to standard error
and terminates the program by calling
abort(3).
The error message includes the name of the file and function containing the
assert()
call, the source code line number of the call, and the text of the argument;
something like:
prog: some_file.c:16: some_func: Assertion `val == 0[aq] failed.
If the macro
NDEBUG
is defined at the moment
<assert.h>
was last included, the macro
assert()
generates no code, and hence does nothing at all.
It is not recommended to define
NDEBUG
if using
assert()
to detect error conditions since the software
may behave no-deterministically.
RETURN VALUE
No value is returned.
ATTRIBUTES
For an explanation of the terms used in this section, see
attributes(7).
| Interface | Attribute | Value
|
|
assert()
| Thread safety | M-Safe
|
STANDARDS
C11, POSIX.-2008.
HISTORY
C89, C99, POSIX.-2001.
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 sid-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)
Index
- NAME
-
- LIBRARY
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ATTRIBUTES
-
- STANDARDS
-
- HISTORY
-
- BUGS
-
- SEE ALSO
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