isinf

Determines whether a floating-point value is an infinity.

Syntax

int isinf(
   /* floating-point */ x
); /* C-only macro */

template <class FloatingType>
inline bool isinf(
   FloatingType x
) throw(); /* C++-only template function */

Parameters

x
The floating-point value to test.

Return value

isinf returns a nonzero value (true in C++ code) if the argument x is a positive or negative infinity. isinf returns 0 (false in C++ code) if the argument is finite or a NAN. Both normal and subnormal floating-point values are considered finite.

Remarks

isinf is a macro when compiled as C, and an inline template function when compiled as C++.

Requirements

Function	Required header (C)	Required header (C++)
isinf	<math.h>	<math.h> or <cmath>

For more compatibility information, see Compatibility.

See also

Math and floating-point support
fpclassify
_fpclass, _fpclassf
isfinite, _finite, _finitef
isnan, _isnan, _isnanf
isnormal