The Open Group Base Specifications Issue 8
IEEE Std 1003.1-2024
Copyright © 2001-2024 The IEEE and The Open Group
NAME
signbit — test sign
SYNOPSIS
#include <math.h>
int signbit(real-floating x);
DESCRIPTION
[CX] ![[Option Start]](../images/opt-start.gif)
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.1-2024 defers to the ISO C
standard.
![[Option End]](../images/opt-end.gif)
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.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
None.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
fpclassify, isfinite,
isinf, isnan, isnormal
XBD <math.h>
CHANGE HISTORY
First released in Issue 6. Derived from the ISO/IEC 9899:1999 standard.
End of informative text.
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