1ASSERT(3) Linux Programmer's Manual ASSERT(3)
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6 assert - abort the program if assertion is false
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9 #include <assert.h>
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11 void assert(scalar expression);
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14 This macro can help programmers find bugs in their programs, or handle
15 exceptional cases via a crash that will produce limited debugging out‐
16 put.
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18 If expression is false (i.e., compares equal to zero), assert() prints
19 an error message to standard error and terminates the program by call‐
20 ing abort(3). The error message includes the name of the file and
21 function containing the assert() call, the source code line number of
22 the call, and the text of the argument; something like:
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24 prog: some_file.c:16: some_func: Assertion `val == 0' failed.
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26 If the macro NDEBUG is defined at the moment <assert.h> was last in‐
27 cluded, the macro assert() generates no code, and hence does nothing at
28 all. It is not recommended to define NDEBUG if using assert() to de‐
29 tect error conditions since the software may behave non-deterministi‐
30 cally.
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33 No value is returned.
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36 For an explanation of the terms used in this section, see at‐
37 tributes(7).
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39 ┌──────────┬───────────────┬─────────┐
40 │Interface │ Attribute │ Value │
41 ├──────────┼───────────────┼─────────┤
42 │assert() │ Thread safety │ MT-Safe │
43 └──────────┴───────────────┴─────────┘
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46 POSIX.1-2001, POSIX.1-2008, C89, C99. In C89, expression is required
47 to be of type int and undefined behavior results if it is not, but in
48 C99 it may have any scalar type.
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51 assert() is implemented as a macro; if the expression tested has side-
52 effects, program behavior will be different depending on whether NDEBUG
53 is defined. This may create Heisenbugs which go away when debugging is
54 turned on.
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57 abort(3), assert_perror(3), exit(3)
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60 This page is part of release 5.10 of the Linux man-pages project. A
61 description of the project, information about reporting bugs, and the
62 latest version of this page, can be found at
63 https://www.kernel.org/doc/man-pages/.
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67GNU 2017-09-15 ASSERT(3)