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template <class T>
struct make_signed
   typedef see-below type;

template <class T> using make_signed_t = typename make_signed<T>::type; // C++11 and above

type: If T is a signed integer type then the same type as T, if T is an unsigned integer type then the corresponding signed type. Otherwise if T is an enumerated or character type (char or wchar_t) then a signed integer type with the same width as T.

If T has any cv-qualifiers then these are also present on the result type.

Requires: T must be an integer or enumerated type, and must not be the type bool.

C++ Standard Reference: 3.9.1.

Compiler Compatibility: All current compilers are supported by this trait.

Header: #include <boost/type_traits/make_signed.hpp> or #include <boost/type_traits.hpp>

Table 1.23. Examples


Result Type



make_signed<unsigned int const>::type

int const

make_signed<const unsigned long long>::type

const long long


A signed integer type with the same width as the enum.


A signed integer type with the same width as wchar_t.