1. Chapter 7: Function

3. Function: Definition Building block of C program.
Group of statements that together perform a task.
Every C program has at least one function, which is main(), and all the most trivial programs can define additional functions.
We can divide up your code into separate functions.
How we divide up your code among different functions is up to us, but logically the division is such that each function performs a specific task.
Eg. printf(), scanf(), sqrt(), pow()

4. Functions Definition

5. Function Definition Contd..

6. Calling the function
Definition of what the function has to do is given while creating function
To use a function, we will have to call that function to perform the defined task.
When a program calls a function, the program control is transferred to the called function. A called function performs a defined task and when its return statement is executed or when its function-ending closing brace is reached, it returns the program control back to the main program.
To call a function, we simply need to pass the required parameters along with the function name, and if the function returns a value, then you can store the returned value.

7. Example 1: Program to find sum of number

8. Example 2: program to find greatest number between two number

9. Example 3: Program to check whether a number is prime or not
Program to generate series of nth prime number
Program to generate prime number between two nymbers

10. Function Prototype
In some compiler if we are going write user defined function after main() we have to prototype the function.
Syntax: datatype function name(date_type, ……..)
Provides following information to function
The name of the function
Return data type
Number of arguments that function accepts

11. Limitation of Return Returns only one value at a time Invalid return
return(a+2, b)
return(x, y)

12. Advantages of Function
Avoid repetition of codes.
Increases program readability.
Divide a complex problem into simpler ones.
Reduces chances of error.
Modifying a program becomes easier by using function.
Easy to debug

13. Categories of Function
Library functions
Built in function, already written, compiled and placed in c library
Eg: printf(), scanf(), sqrt(), pow() ….
User defined function
Defined and used by programmer according to their requirement

14. Categories of User Defined Function
Depending upon the number of arguments and return types used defined function can be categorized as
Function returning value and passing arguments
Function returning no value by passing arguments
Function returning value and passing no arguments
Function returning no value and passing no arguments

15. Function returning value and passing arguments

16. Function returning no value by passing arguments

17. Function returning value and passing no arguments

18. Function returning no value and passing no arguments
Left to you!!!!!!!