ASSERT(3) Linux Programmer's Manual ASSERT(3)
assert - abort the program if assertion is false
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 out-
If expression is false (i.e., compares equal to zero), assert() prints
an error message to standard error and terminates the program by call-
ing 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-deterministi-
No value is returned.
For an explanation of the terms used in this section, see
|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
abort(3), assert_perror(3), exit(3)
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GNU 2017-09-15 ASSERT(3)
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