Swapping two numbers using template function in C++

A significant benefit of object-oriented programming is the reusability of code which eliminates redundant coding. An important feature of C++ is called templates. Templates support generic programming, which allows to development of reusable software components such as functions, classes, etc., supporting different data types in a single framework.

A template is a simple and yet very powerful tool in C++. The simple idea is to pass data type as a parameter so that we don’t need to write the same code for different data types. For example, a software company may need sort() for different data types. Rather than writing and maintaining the multiple codes, we can write one sort() and pass data type as a parameter. The templates declared for functions are called function templates and those declared for classes are called class templates.

This article focuses on discussing how to use a function template to swap two numbers in C++.

Function Templates

There are several functions of considerable importance which have to be used frequently with different data types. The limitation of such functions is that they operate only on a particular data type. It can be overcome by defining that function as a function template or a generic function. A function template specifies how an individual function can be constructed.

Syntax:

template <class T, …… >
returntype FuncName (arguments)
{
    // body of template function
    ………..     
    …………
}

Below is the C++ program to implement the function templates to swap two numbers.

C++

// C++ program to implement
// function templates
#include <iostream>
using namespace std;

// Function template to swap
// two numbers
template <class T>
int swap_numbers(T& x, T& y)
{
    T t;
    t = x;
    x = y;
    y = t;
    return 0;
}

// Driver code
int main()
{
    int a, b;
    a = 10, b = 20;

    // Invoking the swap()
    swap_numbers(a, b);
    cout << a << " " << b << endl;
    return 0;
}

Output:

20 10