isgreater(3) — Linux manual page

isgreater(3)            Library Functions Manual            isgreater(3)

NAME

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

LIBRARY

       Math library (libm, -lm)

SYNOPSIS

       #include <math.h>

       int isgreater(x, y);
       int isgreaterequal(x, y);
       int isless(x, y);
       int islessequal(x, y);
       int islessgreater(x, y);
       int isunordered(x, y);

   Feature Test Macro Requirements for glibc (see
   feature_test_macros(7)):

           All functions described here:
               _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L

DESCRIPTION

       The normal relational operations (like <, "less than") fail if
       one of the operands is NaN.  This will cause an exception.  To
       avoid this, C99 defines the macros listed below.

       These macros are guaranteed to evaluate their arguments only
       once.  The arguments must be of real floating-point type (note:
       do not pass integer values as arguments to these macros, since
       the arguments will not be promoted to real-floating types).

       isgreater()
              determines (x) > (y) without an exception if x or y is
              NaN.

       isgreaterequal()
              determines (x) >= (y) without an exception if x or y is
              NaN.

       isless()
              determines (x) < (y) without an exception if x or y is
              NaN.

       islessequal()
              determines (x) <= (y) without an exception if x or y is
              NaN.

       islessgreater()
              determines (x) < (y) || (x) > (y) without an exception if
              x or y is NaN.  This macro is not equivalent to x != y
              because that expression is true if x or y is NaN.

       isunordered()
              determines whether its arguments are unordered, that is,
              whether at least one of the arguments is a NaN.

RETURN VALUE

       The macros other than isunordered() return the result of the
       relational comparison; these macros return 0 if either argument
       is a NaN.

       isunordered() returns 1 if x or y is NaN and 0 otherwise.

ERRORS

       No errors occur.

ATTRIBUTES

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

VERSIONS

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

STANDARDS

       C11, POSIX.1-2008.

HISTORY

       POSIX.1-2001, C99.

SEE ALSO

       fpclassify(3), isnan(3)

COLOPHON

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Linux man-pages 6.9.1          2024-05-02                   isgreater(3)

Pages that refer to this page: fpclassify(3), math_error(7)

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