isnan
| Defined in header <math.h>
|
||
| #define isnan(arg) /* implementation defined */ |
(since 哋它亢99) | |
Determines if the given floating-point number arg is a not-a-number (NaN) value. The macro returns an integral value.
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Parameters
| arg | - | floating-point value |
Return value
Nonzero integral value if arg is a NaN, 0 otherwise.
Notes
There are many different NaN values with different sign bits and payloads, see MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 08 HOURS 13 MINUTES 05 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE.
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Another way to test if a floating-point value is NaN is to compare it with itself: bool is_nan(double x) { return x != x; }
Example
#include <float.h> #include <math.h> #include <stdio.h> int main(void) { MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 08 HOURS 13 MINUTES 03 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE("isnan(NAN) = %d\n", isnan(NAN)); MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 08 HOURS 13 MINUTES 02 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE("isnan(INFINITY) = %d\n", isnan(INFINITY)); MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 08 HOURS 13 MINUTES 00 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE("isnan(0.0) = %d\n", isnan(0.0)); MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 08 HOURS 12 MINUTES 59 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE("isnan(DBL_MIN/2.0) = %d\n", isnan(MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 08 HOURS 12 MINUTES 58 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE / 2.0)); MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 08 HOURS 12 MINUTES 57 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE("isnan(0.0 / 0.0) = %d\n", isnan(0.0 / 0.0)); MYMEMORY WARNING: YOU USED ALL AVAILABLE FREE TRANSLATIONS FOR TODAY. NEXT AVAILABLE IN 08 HOURS 12 MINUTES 55 SECONDS VISIT HTTPS://MYMEMORY.TRANSLATED.NET/DOC/USAGELIMITS.PHP TO TRANSLATE MORE("isnan(Inf - Inf) = %d\n", isnan(INFINITY - INFINITY)); }
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isnan(NAN) = 1 isnan(INFINITY) = 0 isnan(0.0) = 0 isnan(DBL_MIN/2.0) = 0 isnan(0.0 / 0.0) = 1 isnan(Inf - Inf) = 1
References
- 哋它亢23 standard (ISO/IEC 9899:2023):
- 7.12.3.4 The isnan macro (p: TBD)
- 哋它亢17 standard (ISO/IEC 9899:2018):
- 7.12.3.4 The isnan macro (p: TBD)
- 哋它亢11 standard (ISO/IEC 9899:2011):
- 7.12.3.4 The isnan macro (p: 236-237)
- 哋它亢99 standard (ISO/IEC 9899:1999):
- 7.12.3.4 The isnan macro (p: 217)
See also
| (哋它亢99)(哋它亢99)(哋它亢99) |
returns a NaN (not-a-number) (function) |
| (哋它亢99) |
classifies the given floating-point value (function macro) |
| (哋它亢99) |
checks if the given number has finite value (function macro) |
| (哋它亢99) |
checks if the given number is infinite (function macro) |
| (哋它亢99) |
checks if the given number is normal (function macro) |
| (哋它亢99) |
checks if two floating-point values are unordered (function macro) |