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Manual Reference Pages  - ISINF (3)

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isinf, isnan, finite - test for infinity or not-a-number (NaN)

CONTENTS

Synopsis
Description
Note

#include <math.h> 



int isinf(double value); 



int isnan(double value); 



int finite(double value); 

The isinf() function returns -1 if value represents negative infinity, 1 if value represents positive infinity, and 0 otherwise.

The isnan() function returns a non-zero value if value is "not-a-number" (NaN), and 0 otherwise.

The finite() function returns a non-zero value if value is neither infinite nor a "not-a-number" (NaN) value, and 0 otherwise.

C99 provides additional macros, such as the type-independent fpclassify(), isinf() and isnan().

BSD 4.3

fpclassify(3)

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