From 82ba818ff456bcd6d56a06226e3f27e98fbb55c3 Mon Sep 17 00:00:00 2001 From: Craig Jennings Date: Thu, 14 Aug 2025 22:58:58 -0500 Subject: removing all downloaded devdocs files --- devdocs/c/numeric%2Fmath%2Fisnan.html | 51 ----------------------------------- 1 file changed, 51 deletions(-) delete mode 100644 devdocs/c/numeric%2Fmath%2Fisnan.html (limited to 'devdocs/c/numeric%2Fmath%2Fisnan.html') diff --git a/devdocs/c/numeric%2Fmath%2Fisnan.html b/devdocs/c/numeric%2Fmath%2Fisnan.html deleted file mode 100644 index f9b432de..00000000 --- a/devdocs/c/numeric%2Fmath%2Fisnan.html +++ /dev/null @@ -1,51 +0,0 @@ -

isnan

Defined in header <math.h> 
#define isnan(arg) /* implementation defined */
-		 (since C99)

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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FLT_EVAL_METHOD is ignored: even if the argument is evaluated with more range and precision than its type, it is first converted to its semantic type, and the classification is based on that (this matters if the evaluation type supports NaNs, while the semantic type does not).

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Parameters

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arg - floating point value

Return value

Nonzero integral value if arg is a NaN, ​0​ otherwise.

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Notes

There are many different NaN values with different sign bits and payloads, see nan.

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NaN values never compare equal to themselves or to other NaN values. Copying a NaN may change its bit pattern.

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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; }

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Example

#include <stdio.h>
-#include <math.h>
-#include <float.h>
- 
-int main(void)
-{
-    printf("isnan(NAN)         = %d\n", isnan(NAN));
-    printf("isnan(INFINITY)    = %d\n", isnan(INFINITY));
-    printf("isnan(0.0)         = %d\n", isnan(0.0));
-    printf("isnan(DBL_MIN/2.0) = %d\n", isnan(DBL_MIN/2.0));
-    printf("isnan(0.0 / 0.0)   = %d\n", isnan(0.0/0.0));
-    printf("isnan(Inf - Inf)   = %d\n", isnan(INFINITY - INFINITY));
-}

Possible output:

-
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

See also

- - - - - - -
-
(C99)(C99)(C99)
 returns a NaN (not-a-number)
(function)
-
(C99)
 classifies the given floating-point value
(function macro)
-
(C99)
 checks if the given number has finite value
(function macro)
-
(C99)
 checks if the given number is infinite
(function macro)
-
(C99)
 checks if the given number is normal
(function macro)
-
(C99)
 checks if two floating-point values are unordered
(function macro)
C++ documentation for isnan
-

- © cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
- https://en.cppreference.com/w/c/numeric/math/isnan -

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