isless(3)

1ISGREATER(3)               Linux Programmer's Manual              ISGREATER(3)
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NAME

6       isgreater,    isgreaterequal,   isless,   islessequal,   islessgreater,
7       isunordered - floating-point relational tests without exception for NaN
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SYNOPSIS

10       #include <math.h>
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12       int isgreater(x, y);
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14       int isgreaterequal(x, y);
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16       int isless(x, y);
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18       int islessequal(x, y);
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20       int islessgreater(x, y);
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22       int isunordered(x, y);
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24       Link with -lm.
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26   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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28       All functions described here:
29              _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
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DESCRIPTION

32       The normal relational operations (like <, "less than") fail if  one  of
33       the operands is NaN.  This will cause an exception.  To avoid this, C99
34       defines the macros listed below.
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36       These macros are guaranteed to evaluate their arguments only once.  The
37       arguments  must be of real floating-point type (note: do not pass inte‐
38       ger values as arguments to these macros, since the arguments  will  not
39       be promoted to real-floating types).
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41       isgreater()
42              determines (x) > (y) without an exception if x or y is NaN.
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44       isgreaterequal()
45              determines (x) >= (y) without an exception if x or y is NaN.
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47       isless()
48              determines (x) < (y) without an exception if x or y is NaN.
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50       islessequal()
51              determines (x) <= (y) without an exception if x or y is NaN.
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53       islessgreater()
54              determines (x) < (y) || (x) > (y) without an exception if x or y
55              is NaN.  This macro is not equivalent  to  x != y  because  that
56              expression is true if x or y is NaN.
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58       isunordered()
59              determines whether its arguments are unordered, that is, whether
60              at least one of the arguments is a NaN.
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RETURN VALUE

63       The macros other than isunordered() return the result of the relational
64       comparison; these macros return 0 if either argument is a NaN.
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66       isunordered() returns 1 if x or y is NaN and 0 otherwise.
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ERRORS

69       No errors occur.
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ATTRIBUTES

72       For   an   explanation   of   the  terms  used  in  this  section,  see
73       attributes(7).
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75       ┌───────────────────────────────┬───────────────┬─────────┐
76       │Interface                      │ Attribute     │ Value   │
77       ├───────────────────────────────┼───────────────┼─────────┤
78       │isgreater(), isgreaterequal(), │ Thread safety │ MT-Safe │
79       │isless(), islessequal(),       │               │         │
80       │islessgreater(), isunordered() │               │         │
81       └───────────────────────────────┴───────────────┴─────────┘

CONFORMING TO

83       POSIX.1-2001, POSIX.1-2008, C99.
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NOTES

86       Not all hardware supports these functions, and where  hardware  support
87       isn't provided, they will be emulated by macros.  This will result in a
88       performance penalty.  Don't use these functions if NaN is of no concern
89       for you.
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COLOPHON

95       This  page  is  part of release 5.02 of the Linux man-pages project.  A
96       description of the project, information about reporting bugs,  and  the
97       latest     version     of     this    page,    can    be    found    at
98       https://www.kernel.org/doc/man-pages/.
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102                                  2017-09-15                      ISGREATER(3)