signbit

signbit

Test sign of floating-point number

Portability: C99

   #include <math.h>

   int signbit(floating x);

signbit determines whether its argument is positive or negative by testing the sign bit. Note that zeroes and NaNs may have the sign bit set.

signbit returns 0 if its argument is positive (the sign bit is off), or non-zero if its argument is negative (the sign bit is on).

copysign

SEE ALSO

"Mathematical Functions" in Chapter 2, "Function Categories"