NAME

std::make_signed - std::make_signed

Synopsis

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

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 make_signed is undefined.

Member types

Name Definition
type the signed integer type corresponding to T

Helper types

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

Example

// Run this code

#include <iostream>
#include <type_traits>

int main() {
typedef std::make_signed<unsigned char>::type char_type;
typedef std::make_signed<unsigned int>::type int_type;
typedef std::make_signed<volatile unsigned long>::type long_type;

bool ok1 = std::is_same<char_type, signed char>::value;
bool ok2 = std::is_same<int_type, signed int>::value;
bool ok3 = std::is_same<long_type, volatile signed long>::value;

std::cout << std::boolalpha
<< "char_type is 'signed char'? : " << ok1 << '\n'
<< "int_type is 'signed int'? : " << ok2 << '\n'
<< "long_type is 'volatile signed long'? : " << ok3 << '\n';
}

Output:

char_type is 'signed char'? : true
int_type is 'signed int'? : true
long_type is 'volatile signed long'? : true

See also

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