NAME
signbit — test
sign
SYNOPSIS
#include
<math.h>
int signbit(real-floating x);
DESCRIPTION
[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 POSIX.1-2008 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.
RETURN VALUE
The signbit () macro shall return a
non-zero value if and only if the sign of its argument value is
negative.
ERRORS
No errors are defined.
EXAMPLES
None.
APPLICATION USAGE
None.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
fpclassify(3), isfinite(3), isinf(3), isnan(3), isnormal(3)
XBD <math.h>
CHANGE HISTORY
First released in Issue 6. Derived from the ISO/IEC 9899:1999 (“ISO C99”) standard.