Function in C++

We will learn about the functions in C++. How to declare a function, call functions, function perimeters, and function prototype.

A function is a block of code that performs a specific task on call.

For example, we need to add or multiple two variables. Then we have to create two functions.

• Function to add two variables
• Function to multiple two variable

Here a question arise why we need these function?

The major need of function is to divide a complex problem into smaller parts and makes our program easy to understand and reusable.

There two types of functions.

1. Standard Library function (predefined in C++)
2. User-defined Function ( created by users)

In this post, we will focus on User-defined Function.

User-defined Function in C++

In C++, a programmer can define their own function.

A user-defined function groups code to perform a specific task and that group of code is given a name (identifier).

When the function is invoked from any part of the program, it all executes the codes defined in the body of the function.

Function Declaration in C++

The syntax to declare a function is:

ReturnType FunctionName(Parameter1, Parameter2, Parameter3,.....){
// Function Body
}

Example of Function Declaration

Void Future(){
cout << " Hello Future " << endl;
}

• Name of Function is Future
• Return type is Void
• No Parameters is passes in this function.
• Body of function is written in between {} brackets.

Calling a Function

In the above program, we have declared a function named Future(). To use the Future() function, we need to call it.

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Here’s how we can call the above Future() function.

int main(){
Future()
}

Example 01: Display some text by using a function

#include<iostream>
using namespace std;
// Declaring the functions
void Display(){
cout << " Hello programming World " << endl;
}
int main()
{
calling function
Display();
}

Output:

Hello programming World

Function Parameters

If some values have to pass the function then function have to declare with some parameters.

For example, let us consider the function below:

Here, the int variables a and b are the function parameter.

void Sum(int a, int b){
cout << " sum is " << a + b << endl;
}

We have to pass the values to the function parameter while calling the function.

int main() {
int a= 10, b = 30;
// calling the function
// a and b are passes to the function as an argumaent
Sum(a,b);
return 0;
}

Originally published at https://www.pcslearning.com on October 2, 2022.