ISLESS(3P) POSIX Programmer's Manual ISLESS(3P)PROLOG
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.
NAME
isless — test if x is less than y
SYNOPSIS
#include <math.h>
int isless(real-floating x, real-floating y);
DESCRIPTION
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 isless() macro shall determine whether its first argument is less
than its second argument. The value of isless(x, y) shall be equal to
(x) < (y); however, unlike (x) < (y), isless(x, y) shall not raise the
invalid floating-point exception when x and y are unordered.
RETURN VALUE
Upon successful completion, the isless() macro shall return the value
of (x) < (y).
If x or y is NaN, 0 shall be returned.
ERRORS
No errors are defined.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
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 excep‐
tion 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 expres‐
sion of real-floating type.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSOisgreater(), isgreaterequal(), islessequal(), islessgreater(),
isunordered()
The Base Definitions volume of POSIX.1‐2008, <math.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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.ker‐
nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 ISLESS(3P)
