Class template with multiple parameters

Difficulty Level : Medium
Last Updated : 27 Jun, 2017

While creating templates, it is possible to specify more than one type. We can use more than one generic data type in a class template. They are declared as a comma-separated list within the template as below:
Syntax:

template<class T1, class T2, ...>
class classname
{
      ...
      ...
};

// CPP program to illustrate
// Class template with multiple parameters
  
#include<iostream>
using namespace std;
  
// Class template with two parameters
template<class T1, class T2>
class Test
{
        T1 a;
        T2 b;
    public:
        Test(T1 x, T2 y)
        {
            a = x;
            b = y;
        }
        void show()
        {
            cout << a << " and " << b << endl;
        }
};
  
// Main Function
int main()
{
    // instantiation with float and int type
    Test <float, int> test1 (1.23, 123);
      
    // instantiation with float and char type
    Test <int, char> test2 (100, 'W');   
      
    test1.show();
    test2.show();
      
    return 0;
}

Output:

1.23 and 123
100 and  W

Explanation of the code:

In the above program, the Test constructor has two arguments of generic type.
The type of arguments is mentioned inside angle brackets < > while creating objects.
When argument is more than one, they are separated by commas.
Following statement
```
Test  test1 (1.23, 123);
```
tells the compiler that the first argument is of type float and another one is int type.
During creation of objects, constructor is called and values are received by template arguments.

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