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signbit

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Determines whether a floating-point value is negative.

Syntax

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

inline bool signbit(
   float x
) throw(); /* C++-only overloaded function */

inline bool signbit(
   double x
) throw(); /* C++-only overloaded function */

inline bool signbit(
   long double x
) throw(); /* C++-only overloaded function */

Parameters

x
The floating-point value to test.

Return value

signbit returns a non-zero value (true in C++) if the argument x is negative or negative infinity. It returns 0 (false in C++) if the argument is non-negative, positive infinity, or a NAN.

Remarks

signbit is a macro when compiled as C, and an overloaded inline function when compiled as C++.

Requirements

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

For more compatibility information, see Compatibility.

See also

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