Assigning function to a variable in C++

In C++, assigning a function to a variable and using that variable for calling the function as many times as the user wants, increases the code reusability. Below is the syntax for the same:

Syntax:

C++

// Syntax:

// Below function is assigned to
// the variable fun
auto fun = [&]() {
    cout << "inside function"
         << " variable";
};

Program 1: Below is the C++ program to implement a function assigned to a variable:

C++

// C++ program to implement function
// assigned to a variable

#include <iostream>
using namespace std;

// Driver Code
int main()
{
    // Below function i.e., is
    // assigned to the variable fun
    auto fun
        = [&]() {
              cout << "Inside Function Variable";
          };

    // Call the function using variable
    fun();

    return 0;
}

Output

Inside Function Variable

Program 2: Below is the C++ program to implement a parameterized function assigned to a variable:

C++

// C++ program to implement parameterized
// function assigned to a variable
#include <iostream>
using namespace std;

// Driver Code
int main()
{
    // Passing i and j as 2 parameters
    auto fun = [&](int i, int j) {
        cout << "Parameterized Function";
    };

    // Call the function using variable
    fun(4, 5);

    return 0;
}

Output:

Parameterized Function

Program 3: Below is the C++ program to implement a function assigned to a variable that returns a value:

C++

// C++ program to implement the function
// assigned to a variable returning
// some values
#include <iostream>
using namespace std;

// Driver Code
int main()
{
    // Function taking 2 parameters
    // and returning sum
    auto sum = [&](int a, int b) {
        return a + b;
    };

    // Call the function using variables
    cout << "The sum is: "
         << sum(4, 5);

    return 0;
}

Output

The sum is: 9