This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

       The relational and equality operators  support  the  usual  mathematical  relationships  between  numeric
       values.  For  any  ordered  pair  of numeric values, exactly one of the relationships (less, greater, and
       equal) is true. Relational operators may raise the invalid floating-point exception when argument  values
       are  NaNs.  For a NaN and a numeric value, or for two NaNs, just the unordered relationship is true. This
       macro is a quiet (non-floating-point exception raising) version of a relational operator. It  facilitates
       writing  efficient code that accounts for NaNs without suffering the invalid floating-point exception. In
       the SYNOPSIS section, real-floating indicates that the argument shall be an expression  of  real-floating
       type.

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for  Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical  and  Electronics
       Engineers, Inc and The Open Group.  In the event of any discrepancy between this version and the original
       IEEE  and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document.
       The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are most likely to have  been  introduced
       during   the   conversion  of  the  source  files  to  man  page  format.  To  report  such  errors,  see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                                   2017                                 ISLESSGREATER(3POSIX)

       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.1‐2017 defers to the ISO C standard.

       The  islessgreater()  macro  shall  determine whether its first argument is less than or greater than its
       second  argument.  The  islessgreater(x,  y)  macro  is  similar  to   (x) < (y) || (x) > (y);   however,
       islessgreater(x,  y) shall not raise the invalid floating-point exception when x and y are unordered (nor
       shall it evaluate x and y twice).

       No errors are defined.

       Thefollowingsectionsareinformative.

       None.

       None.

       islessgreater — test if x is less than or greater than y

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.

       None.

       Upon successful completion, the islessgreater() macro shall return the value of (x) < (y) || (x) > (y).

       If x or y is NaN, 0 shall be returned.

isgreater(), isgreaterequal(), isless(), islessequal(), isunordered()

       The Base Definitions volume of POSIX.1‐2017, <math.h>

       #include <math.h>

       int islessgreater(real-floating x, real-floating y);