Summary C++ FUNCTIONS

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C++ Functions
A function is a block of code that performs a specific task.

Suppose we need to create a program to create a circle and color it. We can
create two functions to solve this problem:

• a function to draw the circle

• a function to color the circle

Dividing a complex problem into smaller chunks makes our program easy to
understand and reusable.

There are two types of function:

1. Standard Library Functions: Predefined in C++
2. User-defined Function: Created by users




C++ User-defined Function
C++ allows the programmer to 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.

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C++ Function Declaration

The syntax to declare a function is:

returnType functionName (parameter1, parameter2,...) {
// function body
}


Here's an example of a function declaration.


// function declaration
void greet() {
cout << "Hello World";
}


Here,

• the name of the function is greet()

• the return type of the function is void

• the empty parentheses mean it doesn't have any parameters

• the function body is written inside {}




Calling a Function

In the above program, we have declared a function named greet() . To use
the greet() function, we need to call it.
Here's how we can call the above greet() function.

int main() {

// calling a function
greet();

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}




How Function works in C++




Example 1: Display a Text
#include <iostream>
using namespace std;

// declaring a function
void greet() {
cout << "Hello there!";
}

int main() {

// calling the function
greet();

return 0;
}

Output