Manpage of SIGNBIT

SIGNBIT

Section: Linux Programmer's Manual (3)
Updated: 2016-03-15
Index
 

NAME

signbit - test sign of a real floating-point number  

SYNOPSIS

#include <math.h>

int signbit(x);

Link with -lm.

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

signbit():

_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
 

DESCRIPTION

signbit() is a generic macro which can work on all real floating-point types. It returns a nonzero value if the value of xhas its sign bit set.

This is not the same as x < 0.0, because IEEE 754 floating point allows zero to be signed. The comparison -0.0 < 0.0is false, but signbit(-0.0)will return a nonzero value.

NaNs and infinities have a sign bit.  

RETURN VALUE

The signbit() macro returns nonzero if the sign of xis negative; otherwise it returns zero.  

ERRORS

No errors occur.  

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).
InterfaceAttributeValue
signbit() Thread safetyMT-Safe
 

CONFORMING TO

POSIX.1-2001, POSIX.1-2008, C99. This function is defined in IEC 559 (and the appendix with recommended functions in IEEE 754/IEEE 854).  

SEE ALSO

copysign(3)


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
ATTRIBUTES
CONFORMING TO
SEE ALSO

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Time: 22:27:48 GMT, June 20, 2016