Determines whether the sign of its argument value is negative.

[Classification]

Mathematical library

[Syntax]

#include <math.h>

int signbit(real-floating x); (C99)

[Return value]

If the sign of the argument is negative, a value other than 0 is returned.

If the sign of the argument is positive, 0 is returned.

[Description]

This macro determines whether the sign of its argument value is negative.

If a type other than the floating-point type is passed to the argument, correct operation is not guaranteed.