Templates in C++

               It is a concept which develops generic classes and functions. Using this, you can create a code that helps the user to use the code for any data type without changing the base code.

How to create templates?

Here, is the syntax.

template <typename A, typename B, ...>

eg:

‘template <typename T> T myfunction(T a, T b,……, T n);’

Why templates?

              Templates are useful for the following functionality.

• ·       Reusability.
• ·       Data type safety.
• ·       It makes the implementation easy for vectors, maps and sorting.
• ·       Code duplication is avoided.

The types of templates are given below…

• Class Templates
• Function Templates

• Variable Templates (Since C++ 14)

Let us create a template to add two numbers.

• A template mySum is created with two parameters x,y. ‘Typename’ refers datatype.
• A function definition is included as adding  two numbers.
• This template uses three different data type values to call the mySum().
• Finally, all values are added and the output is displayed.

Program:

#include <iostream>

using namespace std;

template <typename T> T mySum(T x, T y)

{

    return (x + y);

}

int main()

{

    // Using mySum

    cout << "Sum of 5 and 9 is: " << mySum<int>(5, 9) << endl;

    cout << "Sum of 6.5 and 10.5 is :" << mySum<float>(6.5, 10.5) << endl;

    cout <<"Sum of 34.56 and 78.90 is:" << mySum<double>(34.56,78.90) << endl;

    return 0;

}

Output:

Sum of 5 and 9 is: 14

Sum of 6.5 and 10.5 is :17

Sum of 34.56 and 78.90 is:113.46

Let us change this addition code for subtraction.

So, the template can be changed like .

template <typename T> T myDiff(T x, T y)

{

    return (x - y);

}

int main()

{

    // Using myDiff

     cout << "Difference of 9 and 5 is: " << myDiff<int>(9, 5) << endl;

    cout << "Difference of 6.5 and 10.5 is :" << myDiff<float>(6.5, 10.5) << endl;

    cout <<"Difference of 78.90 and 34.56 is:" << myDiff<double>(78.90, 34.56) << endl;          

    return 0;

}

When you compile and run the program, you get the below output.

Difference of 9 and 5 is: 4

Difference of 6.5 and 10.5 is :-4

Difference of 78.90 and 34.56 is:44.34

Hope ,you understood the code. If you have any doubts, comment me in the comments section. Keep Coding!!!