projects / thirdparty / man-pages.git / blame
| Commit | Line | Data |
|---|---|---|
| a1eaacb1 | 1 | '\" t |
| bf5a7247 | 2 | .\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de) |
| fea681da | 3 | .\" |
| 5fbde956 | 4 | .\" SPDX-License-Identifier: Linux-man-pages-copyleft |
| a3605969 | 5 | .\" |
| fea681da MK |
6 | .\" Modified Sat Jul 24 21:42:42 1993 by Rik Faith <faith@cs.unc.edu> |
| 7 | .\" Modified Tue Oct 22 23:44:11 1996 by Eric S. Raymond <esr@thyrsus.com> | |
| f34fcbb8 | 8 | .\" Modified Thu Jun 2 23:44:11 2016 by Nikos Mavrogiannopoulos <nmav@redhat.com> |
| 4c1c5274 | 9 | .TH assert 3 (date) "Linux man-pages (unreleased)" |
| fea681da MK |
10 | .SH NAME |
| 11 | assert \- abort the program if assertion is false | |
| b813014f AC |
12 | .SH LIBRARY |
| 13 | Standard C library | |
| 14 | .RI ( libc ", " \-lc ) | |
| fea681da MK |
15 | .SH SYNOPSIS |
| 16 | .nf | |
| 17 | .B #include <assert.h> | |
| c6d039a3 | 18 | .P |
| fea681da MK |
19 | .BI "void assert(scalar " expression ); |
| 20 | .fi | |
| 21 | .SH DESCRIPTION | |
| 4d644289 MK |
22 | This macro can help programmers find bugs in their programs, |
| 23 | or handle exceptional cases | |
| 24 | via a crash that will produce limited debugging output. | |
| c6d039a3 | 25 | .P |
| 9b3661c4 | 26 | If |
| f34fcbb8 | 27 | .I expression |
| 9b3661c4 MK |
28 | is false (i.e., compares equal to zero), |
| 29 | .BR assert () | |
| 30 | prints an error message to standard error | |
| 31 | and terminates the program by calling | |
| 32 | .BR abort (3). | |
| 33 | The error message includes the name of the file and function containing the | |
| 34 | .BR assert () | |
| 35 | call, the source code line number of the call, and the text of the argument; | |
| 36 | something like: | |
| c6d039a3 | 37 | .P |
| be266c07 MK |
38 | .in +4n |
| 39 | .EX | |
| b957f81f | 40 | prog: some_file.c:16: some_func: Assertion \`val == 0\[aq] failed. |
| be266c07 MK |
41 | .EE |
| 42 | .in | |
| c6d039a3 | 43 | .P |
| fea681da MK |
44 | If the macro |
| 45 | .B NDEBUG | |
| f34fcbb8 | 46 | is defined at the moment |
| bd12ab88 | 47 | .I <assert.h> |
| fea681da | 48 | was last included, the macro |
| 63aa9df0 | 49 | .BR assert () |
| 4d644289 MK |
50 | generates no code, and hence does nothing at all. |
| 51 | It is not recommended to define | |
| f34fcbb8 NM |
52 | .B NDEBUG |
| 53 | if using | |
| 63aa9df0 | 54 | .BR assert () |
| 4d644289 MK |
55 | to detect error conditions since the software |
| 56 | may behave non-deterministically. | |
| 47297adb | 57 | .SH RETURN VALUE |
| fea681da | 58 | No value is returned. |
| d1e3ce2b MS |
59 | .SH ATTRIBUTES |
| 60 | For an explanation of the terms used in this section, see | |
| 61 | .BR attributes (7). | |
| 62 | .TS | |
| 63 | allbox; | |
| c466875e | 64 | lbx lb lb |
| d1e3ce2b MS |
65 | l l l. |
| 66 | Interface Attribute Value | |
| 67 | T{ | |
| 9e54434e BR |
68 | .na |
| 69 | .nh | |
| d1e3ce2b MS |
70 | .BR assert () |
| 71 | T} Thread safety MT-Safe | |
| 72 | .TE | |
| 3113c7f3 | 73 | .SH STANDARDS |
| 4131356c AC |
74 | C11, POSIX.1-2008. |
| 75 | .SH HISTORY | |
| 76 | C89, C99, POSIX.1-2001. | |
| c6d039a3 | 77 | .P |
| e0089d55 AC |
78 | In C89, |
| 79 | .I expression | |
| 80 | is required to be of type | |
| 81 | .I int | |
| 82 | and undefined behavior results if it is not, but in C99 | |
| 83 | it may have any scalar type. | |
| 84 | .\" See Defect Report 107 for more details. | |
| fea681da | 85 | .SH BUGS |
| 63aa9df0 | 86 | .BR assert () |
| fea681da | 87 | is implemented as a macro; if the expression tested has side-effects, |
| d9bfdb9c | 88 | program behavior will be different depending on whether |
| fea681da | 89 | .B NDEBUG |
| c13182ef MK |
90 | is defined. |
| 91 | This may create Heisenbugs which go away when debugging | |
| fea681da | 92 | is turned on. |
| 47297adb | 93 | .SH SEE ALSO |
| fea681da MK |
94 | .BR abort (3), |
| 95 | .BR assert_perror (3), | |
| 96 | .BR exit (3) |