Std::is_same (3) Linux Manual Page

std::is_same – std::is_same

Synopsis

Defined in header<type_traits>

    template <class T, class U>
    (since C++ 11)

        struct is_same;

If T and U name the same type (including const/volatile qualifications), provides the member constant value equal to true. Otherwise value is false.
Commutativity is satisfied, i.e. for any two types T and U, is_same<T, U>::value == true if and only if is_same<U, T>::value == true.
Helper variable template

template< class T, class U >                             (since C++17)

inline constexpr bool is_same_v = is_same<T, U>::value;

Inherited from std::integral_constant

Member constants

value true if T and U is the same type , false otherwise
(public static member constant)
[static]

Member functions

converts the object to bool, returns value
operator bool (public member function)

operator() returns value
(public member function)
(C++14)

Member types

Type Definition
value_type bool
type std::integral_constant<bool, value>

Possible implementation

template<class T, class U>
struct is_same : std::false_type {};

template<class T>
struct is_same<T, T> : std::true_type {};

Example

// Run this code

#include <iostream>

#include <type_traits>

#include <cstdint>
void print_separator()

{
    std::cout << "-----\n";
}
int main()

{
    std::cout << std::boolalpha;
    // some implementation-defined facts
    std::cout << std::is_same<int, std::int32_t>::value << '\n';
    // usually true if 'int' is 32 bit
    std::cout << std::is_same<int, std::int64_t>::value << '\n';
    // possibly true if ILP64 data model is used
    print_separator();
    // 'float' is never an integral type
    std::cout << std::is_same<float, std::int32_t>::value << '\n'; // false
    print_separator();
    // 'int' is implicitly 'signed'
    std::cout << std::is_same<int, int>::value << "\n";          // true
    std::cout << std::is_same<int, unsigned int>::value << "\n"; // false
    std::cout << std::is_same<int, signed int>::value << "\n";   // true
    print_separator();
    // unlike other types, 'char' is neither 'unsigned' nor 'signed'
    std::cout << std::is_same<char, char>::value << "\n";          // true
    std::cout << std::is_same<char, unsigned char>::value << "\n"; // false
    std::cout << std::is_same<char, signed char>::value << "\n";   // false
}

Possible output:

  true
  false
  —–
  false
  —–
  true
  false
  true
  —–
  true
  false
  false

std::is_same (3) Linux Manual Page