IEEE754 fp

[Ravishankar S]

Hello C-Experts,

Is there any predefined constant in Std C which specifed that the
implementation uses the IEEE754
standard for floating point operation ?

Regards,
Ravishankar

 

[Ben Pfaff]

Is there any predefined constant in Std C which specifed that the
implementation uses the IEEE754
standard for floating point operation ?

C99 has __STDC_IEC_559__:

F.1 Introduction
1 This annex specifies C language support for the IEC 60559
floating-point standard. The IEC 60559 floating-point
standard is specifically Binary floating-point arithmetic
for microprocessor systems, second edition (IEC 60559:1989),
previously designated IEC 559:1989 and as IEEE Standard for
Binary Floating-Point Arithmetic (ANSI/IEEE 754-1985). IEEE
Standard for Radix-Independent Floating-Point Arithmetic
(ANSI/IEEE 854-1987) generalizes the binary standard to
remove dependencies on radix and word length. IEC 60559
generally refers to the floating-point standard, as in IEC
60559 operation, IEC 60559 format, etc. An implementation
that defines __STDC_IEC_559__ shall conform to the
specifications in this annex. Where a binding between the C
language and IEC 60559 is indicated, the IEC 60559-specified
behavior is adopted by reference, unless stated otherwise.

 

[Martin Ambuhl]

Hello C-Experts,

Is there any predefined constant in Std C which specifed that the
implementation uses the IEEE754
standard for floating point operation ?

Note that the ANSI/IEEE 754, ANSI/IEEE 854, and IEC 559 designations
have been superseded by IEEE 60559.

If the implementation defines __STDC_IEC_559__ (the old name is used in
the macro) then the implementation shall conform to IEC 60559, in the
way specified in the annex to the C standard.

 

[Army1987]

Hello C-Experts,

Is there any predefined constant in Std C which specifed that the
implementation uses the IEEE754
standard for floating point operation ?

__STDC_IEC_559__
But note that there are many implementations which partially conform to
the Annex F, and do not define __STDC_IEC_559__, even if, for example,
floating point numbers are stored with the IEEE754 representation.