std:: make_signed

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make_signed
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(C++11) ( until C++20* ) (C++17)
Compile-time rational arithmetic
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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)

If the program adds specializations for std::make_signed , the behavior 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

#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

(C++11)
checks if a type is a signed arithmetic type
(class template)
checks if a type is an unsigned arithmetic type
(class template)
obtains the corresponding signed type for the given integral type
(class template)