NAME

isgreater, isgreaterequal, isless, islessequal, islessgreater — real-floating relational tests

SYNOPSIS

#include <math.h>

int isgreater(real-floating x, real-floating y);
int isgreaterequal(real-floating x, real-floating y);
int isless(real-floating x, real-floating y);
int islessequal(real-floating x, real-floating y);
int islessgreater(real-floating x, real-floating y);


DESCRIPTION

^[CX] 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 POSIX.1-2024 defers to the ISO C standard.

The isgreater() macro shall determine whether its first argument is greater than its second argument. The value of isgreater(x, y) shall be equal to (x) > (y); however, unlike (x) > (y), isgreater(x, y) shall not raise the invalid floating-point exception when x and y are unordered.

The isgreaterequal() macro shall determine whether its first argument is greater than or equal to its second argument. The value of isgreaterequal(x, y) shall be equal to (x) >= (y); however, unlike (x) >= (y), isgreaterequal(x, y) shall not raise the invalid floating-point exception when x and y are unordered.

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.

The islessequal() macro shall determine whether its first argument is less than or equal to its second argument. The value of islessequal(x, y) shall be equal to (x) <= (y); however, unlike (x) <= (y), islessequal(x, y) shall not raise the invalid floating-point exception when x and y are unordered.

The islessgreater() macro shall determine whether its first argument is less than or greater than its second argument. The islessgreater(x, y) macro is similar to (x) < (y) || (x) > (y); however, islessgreater(x, y) shall not raise the invalid floating-point exception when x and y are unordered (nor shall it evaluate x and y twice).

^[MX] Relational operators and their corresponding comparison macros shall produce equivalent result values, even if argument values are represented in wider formats. Thus, comparison macro arguments represented in formats wider than their semantic types shall not be converted to the semantic types, unless the wide evaluation method converts operands of relational operators to their semantic types. The standard wide evaluation methods characterized by FLT_EVAL_METHOD equal to 1 or 2 (see <float.h>) do not convert operands of relational operators to their semantic types.

RETURN VALUE

Upon successful completion, the isgreater() macro shall return the value of (x) > (y).

Upon successful completion, the isgreaterequal() macro shall return the value of (x) >= (y).

Upon successful completion, the isless() macro shall return the value of (x) < (y).

Upon successful completion, the islessequal() macro shall return the value of (x) <= (y).

Upon successful completion, the islessgreater() macro shall return the value of (x) < (y) || (x) > (y).

If x or y is NaN, these functions shall return 0.

ERRORS

No errors are defined.

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

isunordered

XBD <float.h>, <math.h>

CHANGE HISTORY

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

Issue 8

The individual pages for these functions have been merged to form a single page, to reduce duplication.

Austin Group Defect 1302 is applied, aligning these functions with the ISO/IEC 9899:2018 standard.