std::make_signed

 

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Defined in header <type_traits>
template< class T > struct make_signed;		(since C++11)

If T is an integral (except bool) or enumeration type, provides the member typedef type which is the signed integer type corresponding to T, with the same cv-qualifiers.

If T is signed or unsigned char, short, int, long, long long, the signed type from this list corresponding to T is provided.

If T is an enumeration type or char, wchar_t, char8_t (since C++20), char16_t, char32_t, the signed integer type with the smallest rank having the same sizeof as T is provided.

Otherwise, the behavior is undefined.	(until C++20)
Otherwise, the program is ill-formed.	(since C++20)

The behavior of a program that adds specializations for std::make_signed is undefined.

Member types

Name	Definition
type	the signed integer type corresponding to T

Helper types

template< class T > using make_signed_t = typename make_signed<T>::type;		(since C++14)

Example

Run this code

#include <type_traits>
 
enum struct E : unsigned short {};
 
int main()
{
    using char_type = std::make_signed_t<unsigned char>;
    using int_type  = std::make_signed_t<unsigned int>;
    using long_type = std::make_signed_t<volatile unsigned long>;
    using enum_type = std::make_signed_t<E>;
 
    static_assert(
        std::is_same_v<char_type, signed char> and
        std::is_same_v<int_type, signed int> and
        std::is_same_v<long_type, volatile signed long> and
        std::is_same_v<enum_type, signed short>
    );
}

See also

is_signed (C++11)	checks if a type is a signed arithmetic type (class template)
is_unsigned (C++11)	checks if a type is an unsigned arithmetic type (class template)
make_unsigned (C++11)	makes the given integral type unsigned (class template)