signbit(3) 맨 페이지 - 윈디하나의 솔라나라

개요

섹션
맨 페이지 이름
검색(S)

signbit(3)

SIGNBIT(3)                 Linux Programmer's Manual                SIGNBIT(3)

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 x has 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 < 0.0 is false, but sign‐
       bit(-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 x is negative;  oth‐
       erwise it returns zero.

ERRORS
       No errors occur.

ATTRIBUTES
       For  an  explanation  of  the  terms  used in this section, see attrib‐
       utes(7).  allbox; lb lb lb l l l.  Interface Attribute Value  T{  sign‐
       bit() T}   Thread safety  MT-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)

COLOPHON
       This page is part of release 5.02 of the Linux  man-pages  project.   A
       description  of  the project, information about reporting bugs, and the
       latest    version    of    this    page,    can     be     found     at
       https://www.kernel.org/doc/man-pages/.

GNU                               2017-09-15                        SIGNBIT(3)
맨 페이지 내용의 저작권은 맨 페이지 작성자에게 있습니다.
RSS ATOM XHTML 5 CSS3