#include <type_traits>

template <class A, class B>
struct is_same

template <class A, class B>
inline constexpr 
       bool is_same_v
         = is_same<A, B>::value

std::is_same<A, B>::value

// C++中演示std::is_same的程序
#include <bits/stdc++.h>
#include <type_traits>
using namespace std;
  
// 主函数
int main()
{
  
    cout << boolalpha;
  
    cout << "is int & int32_t相同吗? "
         << is_same<int, int32_t>::value
         << endl;
  
    cout << "is int & int64_t相同吗? "
         << is_same<int, int64_t>::value
         << endl;
  
    cout << "is float & int32_t相同吗? "
         << is_same<float, int32_t>::value
         << endl;
  
    cout << "is int & int相同吗? "
         << is_same<int, int>::value << endl;
    cout << "is int & unsigned int相同吗? "
         << is_same<int, unsigned int>::value
         << endl;
  
    cout << "is int & signed int相同吗? "
         << is_same<int, signed int>::value
         << endl;
  
    return 0;
}

is int & int32_t相同吗? true
is int & int64_t相同吗? false
is float & int32_t相同吗? false
is int & int相同吗? true
is int & unsigned int相同吗? false
is int & signed int相同吗? true

//C++示例程序，演示std::is_same的用法
#include <bits/stdc++.h>
#include <type_traits>
using namespace std;
  
typedef int integer_type;
  
//声明结构体
struct A {
    int x, y;
};
struct B {
    int x, y;
};
typedef A C;
  
//主函数
int main()
{
  
    cout << boolalpha;
  
    cout << "is_same:" << endl;
    cout << "int, const int is_same: "
         << is_same<int, const int>::value
         << endl;
  
    cout << "int, integer_type is_same: "
         << is_same<int, integer_type>::value
         << endl;
  
    cout << "A, B is_same: "
         << is_same<A, B>::value
         << endl;
  
    cout << "A, C is_same: "
         << is_same<A, C>::value
         << endl;
  
    cout << "signed char, int8_t is_same: "
         << is_same<signed char, int8_t>::value
         << endl;
  
    return 0;
}

is_same:
int, const int is_same: false
int, integer_type is_same: true
A, B is_same: false
A, C is_same: true
signed char, int8_t is_same: true