Type trait arithmetic

Type trait `arithmetic_rank`

In C++, the term arithmetic type refers to a fundamental type which is either integral or floating point.

As part of the definition of safely_constructible, strict_variant makes a finer classification of these types, and assigns a portable conversion rank to each such type.

The type trait arithmetic_rank computes the rank of a given arithmetic type.

Valid Expressions

expression	value
`T`	any arithmetic type
`strict_variant::mpl::arithmetic_rank<T>::value`	An `int` representing the conversion rank of `T`, within its category

Definition

Note that for strict_variant, comparing these numbers is only meaningful within an arithmetic category.

The purpose of these numbers is, if C++ permits A to be narrower than B, and A and B are in the same category, then A has a lower rank than B.

Fundmental Type	arithmetic rank
`(unsigned) short`	`0`
`(unsigned) int`	`1`
`(unsigned) long`	`2`
`(unsigned) long long`	`3`
`signed char`	`0`
`char`	`0`
`unsigned char`	`0`
`char16_t`	`1`
`char32_t`	`2`
`float`	`0`
`double`	`1`
`long double`	`2`
`bool`	`0`
`wchar_t`	`0`

Note

	Note
You are free to specialize this trait to support other arithmetic types, such as implementation-specific extended integers. If you have e.g. an 128 bit integer type which you want to support, most likely you want to define its rank to be `4` by specializing this trait.

You are free to specialize this trait to support other arithmetic types, such as implementation-specific extended integers.

If you have e.g. an 128 bit integer type which you want to support, most likely you want to define its rank to be 4 by specializing this trait.