islessequal(3)

1isgreater(3)               Library Functions 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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LIBRARY

10       Math library (libm, -lm)
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SYNOPSIS

13       #include <math.h>
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15       int isgreater(x, y);
16       int isgreaterequal(x, y);
17       int isless(x, y);
18       int islessequal(x, y);
19       int islessgreater(x, y);
20       int isunordered(x, y);
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22   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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24           All functions described here:
25               _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
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DESCRIPTION

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

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

65       No errors occur.
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ATTRIBUTES

68       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
69       tributes(7).
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71       ┌────────────────────────────────────────────┬───────────────┬─────────┐
72       │Interface                                   │ Attribute     │ Value   │
73       ├────────────────────────────────────────────┼───────────────┼─────────┤
74       │isgreater(), isgreaterequal(), isless(),    │ Thread safety │ MT-Safe │
75       │islessequal(), islessgreater(),             │               │         │
76       │isunordered()                               │               │         │
77       └────────────────────────────────────────────┴───────────────┴─────────┘
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VERSIONS

80       Not all hardware supports these functions, and where  hardware  support
81       isn't provided, they will be emulated by macros.  This will result in a
82       performance penalty.  Don't use these functions if NaN is of no concern
83       for you.
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STANDARDS

86       C11, POSIX.1-2008.
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HISTORY

89       POSIX.1-2001, C99.
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