signbit - test sign
int signbit(real-floating x);
[CX] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of IEEE Std 1003.1-2001 defers to the ISO C standard.
The signbit() macro shall determine whether the sign of its argument value is negative. NaNs, zeros, and infinities have a sign bit.
The signbit() macro shall return a non-zero value if and only if the sign of its argument value is negative.
No errors are defined.
fpclassify(), isfinite(), isinf(), isnan(), isnormal(), the Base Definitions volume of IEEE Std 1003.1-2001, <math.h>
First released in Issue 6. Derived from the ISO/IEC 9899:1999 standard.