[depr.c.macros]

# Annex D (normative) Compatibility features [[depr]](./#depr)

## D.11 Deprecated C macros [depr.c.macros]

[1](#1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/future.tex#L222)

The header [<cfloat>](cfloat.syn#header:%3ccfloat%3e "17.3.7 Header <cfloat> synopsis [cfloat.syn]") has the following macros:#define FLT_HAS_SUBNORM *see below*#define DBL_HAS_SUBNORM *see below*#define LDBL_HAS_SUBNORM *see below*#define DECIMAL_DIG *see below*

The header defines these macros the same as
the C standard library header [<float.h>](support.c.headers.general#header:%3cfloat.h%3e "17.15.1 General [support.c.headers.general]")[.](#1.sentence-2)

See also: ISO/IEC 9899:2024, 5.2.4.2.2, 7.33.5

[2](#2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/future.tex#L235)

In addition to being available via inclusion of the [<cfloat>](cfloat.syn#header:%3ccfloat%3e "17.3.7 Header <cfloat> synopsis [cfloat.syn]") header,
the macros INFINITY and NAN are
available when [<cmath>](cmath.syn#header:%3ccmath%3e "29.7.1 Header <cmath> synopsis [cmath.syn]") is included[.](#2.sentence-1)

See also: ISO/IEC 9899:2024, 7.12

[3](#3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/future.tex#L242)

The header [<stdbool.h>](stdbool.h.syn#header:%3cstdbool.h%3e "17.15.5 Header <stdbool.h> synopsis [stdbool.h.syn]") has the following macro:#define __bool_true_false_are_defined 1

See also: ISO/IEC 9899:2024, 7.19