isless (original) (raw)

The Open Group Base Specifications Issue 6
IEEE Std 1003.1, 2004 Edition
Copyright © 2001-2004 The IEEE and The Open Group, All Rights reserved.

A newer edition of this document exists here

NAME

isless - test if x is less than y

SYNOPSIS

`#include <math.h>

int isless(real-floating

x, real-floating y);
`

DESCRIPTION

[CX] [Option Start] 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 IEEE Std 1003.1-2001 defers to the ISO C standard. [Option End]

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 exception 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 expression of real-floating type.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

isgreater(), isgreaterequal(), islessequal(), islessgreater(), isunordered(), the Base Definitions volume of IEEE Std 1003.1-2001, <math.h>

CHANGE HISTORY

First released in Issue 6. Derived from the ISO/IEC 9899:1999 standard.

End of informative text.

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