signbit(3)

determine whether a floating-point number's sign is negative

NAME

signbit – determine whether a floating-point number's sign is negative

Math Library (libm, -lm)

#include <math.h>

int

signbit(real-floating x);

The signbit() macro takes an argument of x and returns non-zero if the value of its sign is negative, otherwise 0.

The signbit() macro conforms to ISO/IEC 9899:1999 (“ISO C99”).

The signbit() macro was added in FreeBSD 5.1.