c99 [ flag... ] file... –lm [ library... ] #include <math.h> int signbit(real-floating x);
The signbit() macro determines whether the sign of its argument value is negative. NaNs, zeros, and infinities have a sign bit.
The signbit() macro returns a non-zero value if and only if the sign of its argument value is negative.
No errors are defined.
See attributes(5) for descriptions of the following attributes:
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fpclassify(3M), isfinite(3M), isinf(3M), isnan(3M), isnormal(3M), math.h(3HEAD), attributes (5), standards(5)