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