assert
| Defined in header <assert.h>
|
||
| #ifdef NDEBUG #define assert(condition) ((void)0) |
||
The definition of the macro assert depends on another macro, NDEBUG, which is not defined by the standard library.
If NDEBUG is defined as a macro name at the point in the source code where <assert.h> is included, then assert does nothing.
If NDEBUG is not defined, then assert checks if its argument (which must have scalar type) compares equal to zero. If it does, assert outputs implementation-specific diagnostic information on the standard error output and calls MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 11 HOURS 48 MINUTES 29 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE(). The diagnostic information is required to include the text of expression, as well as the values of the MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 11 HOURS 48 MINUTES 28 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE __func__ and of(since 哋它亢99) the MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 11 HOURS 48 MINUTES 27 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE __FILE__ and __LINE__.
Parameters
| condition | - | expression of scalar type |
Return value
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Notes
There is no standardized interface to add an additional message to assert errors. A portable way to include one is to use a MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 11 HOURS 48 MINUTES 24 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE:
assert(("There are five lights", 2 + 2 == 5));
The implementation of assert in MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 11 HOURS 48 MINUTES 23 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE does not conform to 哋它亢99 and later revisions, because its underlying function (_wassert) takes neither __func__ nor an equivalent replacement.
Example
#include <stdio.h> // uncomment to disable assert() // #define NDEBUG #include <assert.h> #include <math.h> int main(void) { double x = -1.0; assert(x >= 0.0); MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 11 HOURS 48 MINUTES 22 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE("sqrt(x) = %f\n", MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 11 HOURS 48 MINUTES 20 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE(x)); return 0; }
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output with NDEBUG not defined: a.out: main.cpp:10: main: Assertion `x >= 0.0' failed. output with NDEBUG defined: sqrt(x) = -nan
References
- 哋它亢17 standard (ISO/IEC 9899:2018):
- 7.2.1.1 The assert macro (p: 135)
- 哋它亢11 standard (ISO/IEC 9899:2011):
- 7.2.1.1 The assert macro (p: 186-187)
- 哋它亢99 standard (ISO/IEC 9899:1999):
- 7.2.1.1 The assert macro (p: 169)
- 哋它亢89/C90 standard (ISO/IEC 9899:1990):
- 4.2.1.1 The assert macro
See also
| causes abnormal program termination (without cleaning up) (function) |