1ISLESS(3P)                 POSIX Programmer's Manual                ISLESS(3P)
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PROLOG

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

13       isless — test if x is less than y
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SYNOPSIS

16       #include <math.h>
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18       int isless(real-floating x, real-floating y);
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DESCRIPTION

21       The functionality described on this reference page is aligned with  the
22       ISO C  standard.  Any  conflict between the requirements described here
23       and the ISO C standard is unintentional. This  volume  of  POSIX.1‐2008
24       defers to the ISO C standard.
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26       The  isless()  macro shall determine whether its first argument is less
27       than its second argument. The value of isless(x, y) shall be  equal  to
28       (x) < (y);  however, unlike (x) < (y), isless(x, y) shall not raise the
29       invalid floating-point exception when x and y are unordered.
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RETURN VALUE

32       Upon successful completion, the isless() macro shall return  the  value
33       of (x) < (y).
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35       If x or y is NaN, 0 shall be returned.
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ERRORS

38       No errors are defined.
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40       The following sections are informative.
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EXAMPLES

43       None.
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APPLICATION USAGE

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

59       None.
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FUTURE DIRECTIONS

62       None.
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SEE ALSO

65       isgreater(),    isgreaterequal(),    islessequal(),    islessgreater(),
66       isunordered()
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68       The Base Definitions volume of POSIX.1‐2008, <math.h>
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71       Portions of this text are reprinted and reproduced in  electronic  form
72       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
73       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
74       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
75       cal and Electronics Engineers,  Inc  and  The  Open  Group.   (This  is
76       POSIX.1-2008  with  the  2013  Technical Corrigendum 1 applied.) In the
77       event of any discrepancy between this version and the original IEEE and
78       The  Open Group Standard, the original IEEE and The Open Group Standard
79       is the referee document. The original Standard can be  obtained  online
80       at http://www.unix.org/online.html .
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82       Any  typographical  or  formatting  errors that appear in this page are
83       most likely to have been introduced during the conversion of the source
84       files  to  man page format. To report such errors, see https://www.ker‐
85       nel.org/doc/man-pages/reporting_bugs.html .
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89IEEE/The Open Group                  2013                           ISLESS(3P)
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