////
Copyright 2024 Matt Borland
Distributed under the Boost Software License, Version 1.0.
https://www.boost.org/LICENSE_1_0.txt
////

[#cfloat]
= `<cfloat>` Support
:idprefix: cfloat_

Macros analogous to those from https://en.cppreference.com/w/cpp/header/cfloat.html[`<cfloat>`] are provided by the library.
These macros are not available when consuming the library as a module.
In all cases `std::numeric_limits` should be preferred.

[source, c++]
----
#include <boost/decimal/cfloat.hpp>


// Number of digits in the coefficient
#define BOOST_DECIMAL_DEC32_MANT_DIG  std::numeric_limits<boost::decimal::decimal32_t>:digits10
#define BOOST_DECIMAL_DEC64_MANT_DIG  std::numeric_limits<boost::decimal::decimal64_t>:digits10
#define BOOST_DECIMAL_DEC128_MANT_DIG std::numeric_limits<boost::decimal::decimal128_t>:digits10

// Minimum exponent
#define BOOST_DECIMAL_DEC32_MIN_EXP  std::numeric_limits<boost::decimal::decimal32_t>:min_exponent
#define BOOST_DECIMAL_DEC64_MIN_EXP  std::numeric_limits<boost::decimal::decimal64_t>:min_exponent
#define BOOST_DECIMAL_DEC128_MIN_EXP std::numeric_limits<boost::decimal::decimal128_t>:min_exponent

// Maximum exponent
#define BOOST_DECIMAL_DEC32_MAX_EXP  std::numeric_limits<boost::decimal::decimal32_t>:max_exponent
#define BOOST_DECIMAL_DEC64_MAX_EXP  std::numeric_limits<boost::decimal::decimal64_t>:max_exponent
#define BOOST_DECIMAL_DEC128_MAX_EXP std::numeric_limits<boost::decimal::decimal128_t>:max_exponent

// Maximum Finite Value
#define BOOST_DECIMAL_DEC32_MAX  std::numeric_limits<boost::decimal::decimal32_t>::max()
#define BOOST_DECIMAL_DEC64_MAX  std::numeric_limits<boost::decimal::decimal64_t>::max()
#define BOOST_DECIMAL_DEC128_MAX std::numeric_limits<boost::decimal::decimal128_t>::max()

// Minimum positive normal vlaue
#define BOOST_DECIMAL_DEC32_MIN std::numeric_limits<boost::decimal::decimal32_t>::min()
#define BOOST_DECIMAL_DEC64_MIN   std::numeric_limits<boost::decimal::decimal64_t>::min()
#define BOOST_DECIMAL_DEC128_MIN std::numeric_limits<boost::decimal::decimal128_t>::min()

// Minimum positive sub-normal value
#define BOOST_DECIMAL_DEC32_MAX  std::numeric_limits<boost::decimal::decimal32_t>::denorm_min()
#define BOOST_DECIMAL_DEC64_MAX  std::numeric_limits<boost::decimal::decimal64_t>::denorm_min()
#define BOOST_DECIMAL_DEC128_MAX std::numeric_limits<boost::decimal::decimal128_t>::denorm_min()
----

Additionally `BOOST_DECIMAL_DEC_EVAL_METHOD` is similar to https://en.cppreference.com/w/cpp/types/climits/FLT_EVAL_METHOD[`FLT_EVAL_METHOD`]:

The valid values are:

|===
| Value | Description
| 0 | All operations evaluated in the range and precision of the native type
| 1 | All `decimal32_t` (or `decimal_fast32_t`) operations are evaluated with the precision and range of `decimal64_t` internally, and returned as `decimal64_t`
| 2 | All `decimal32_t` and `decimal64_t` (or fast equivalents) operations are evaluated with the precision and range of `decimal128_t` internally, and returned as the original type.
|===

To use the functionality you must `#define BOOST_DECIMAL_DEC_EVAL_METHOD` to the value you want before you `#include <boost/decimal.hpp>`, or any Boost.Decimal header if you are not using the convenience header.
