std::is_same template in C++ with Examples
Last Updated :
08 Jun, 2020
The std::is_same template of C++ STL is present in the <type_traits> header file. The std::is_same template of C++ STL is used to check whether the type A is same type as of B or not. It return the boolean value true if both are same, otherwise return false.
Header File:
#include<type_traits>
Template Class:
template <class A, class B>
struct is_same
template <class A, class B>
inline constexpr
bool is_same_v
= is_same<A, B>::value
Syntax:
std::is_same<A, B>::value
Parameters: This std::is_same template accepts the following parameters:
- A: It represent the first type.
- B: It represent the second type.
Return Value: The template std::is_same returns a boolean variable as shown below:
- True: If the type A is same as the type B.
- False: If the type A is not same as the type B.
Below is the program to demonstrate std::is_same in C++:
Program:
#include <bits/stdc++.h>
#include <type_traits>
using namespace std;
int main()
{
cout << boolalpha;
cout << "is int & int32_t is same? "
<< is_same< int , int32_t>::value
<< endl;
cout << "is int & int64_t is same? "
<< is_same< int , int64_t>::value
<< endl;
cout << "is float & int32_t is same? "
<< is_same< float , int32_t>::value
<< endl;
cout << "is int & int is same? "
<< is_same< int , int >::value << endl;
cout << "is int & unsigned int is same? "
<< is_same< int , unsigned int >::value
<< endl;
cout << "is int & signed int is same? "
<< is_same< int , signed int >::value
<< endl;
return 0;
}
|
Output:
is int & int32_t is same? true
is int & int64_t is same? false
is float & int32_t is same? false
is int & int is same? true
is int & unsigned int is same? false
is int & signed int is same? true
Program 2:
#include <bits/stdc++.h>
#include <type_traits>
using namespace std;
typedef int integer_type;
struct A {
int x, y;
};
struct B {
int x, y;
};
typedef A C;
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;
}
|
Output:
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
Reference: http://www.cplusplus.com/reference/type_traits/is_same/
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