assert - abort the program if assertion is false
#include <assert.h>
void assert(scalar expression);
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' 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
non-deterministically.
No value is returned.
For an explanation of the terms used in this section, see
attributes(7).
Interface |
Attribute |
Value |
assert () |
Thread safety |
MT-Safe |
POSIX.1-2001, POSIX.1-2008, 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.
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.
abort(3),
assert_perror(3),
exit(3)