Class template with multiple parameters

Prerequisite: Templates in C++

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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