Functions are named blocks of code that perform actions and are executed when called by name. There are two types of functions: user-defined functions written by programmers and built-in functions that are part of the language, such as sqrt(), pow(), rand(), and clock(). Functions provide a modular way to structure programs by dividing program logic into smaller subroutines. User-defined functions consist of a function declaration, which defines the name and parameters, and a function definition, which contains the code. Functions can return a single value using the return statement, with the return type specified in the function declaration.

1. Source: Let us C by Yashwant Kanitkar

2. Functions
• named block of code
• perform some actions.
• executed when called by name.
• Unique name.
Source: Let us C by Yashwant Kanitkar

3. .. Building blocks of Function :
•provide a structured programming
approach.
•modular way of programming.
• The whole program logic is divided
into smaller modules or functions.

4. Types of Functions
C++ language provides the
following types of functions:
User Defined Functions
Built in Function
Source: Let us C by Yashwant Kanitkar

5. User Defined Functions
A type of function written by programmer
is known as user-defined function.
User defined function has a unique name.
User-defined function consist of the
following:
 Function declaration
 Function definition
Source: Let us C by Yashwant Kanitkar

6. Built – in Function
A type of function that is available as a
part of language is known as built - in
function or library function . There
are many functions and some of
those are:
 sqrt(number);
 pow(x,y);
 rand( );
 clock( );
Source: Let us C by Yashwant Kanitkar

7. Returning Value from
Function
 can return a single value.
 indicates the type of value
For example
int is used as return type
 if the function returns the integer value .
Syntax
The syntax for returning a value is as follows:
return expression;
Source: Let us C by Yashwant Kanitkar

8. Program
#include <iostream.h>
#include <conio.h>
Int cube(int);
Void main()
{
int n , c;
cout<<“Enter number:”;
cin>>n;
c = cube(n);
cout<<“cube is”<<c;
getch();
}
Int cube(int num)
{
return num * num * num;
}
Enter number : 4
Cube is : 64
Output
Returning value
Example:
Source: Let us C by Yashwant Kanitkar

9. Any Question ?

10. Any Question ?