1. Functions, Return Values, Parameters Getters and Setters

2. Procedures in Everyday Life
We use procedures all time – fire drill or recipe
They are set up in advance with a detailed set of instructions
We only refer to them (Call them) when we need them
Procedures allow us to repeat the same task over and over again

3. Function Procedures Procedures in programming languages are the same
They are set up in advance with a detailed set of instructions
We only refer to them (Call them) when we need them
Procedures allow us to repeat the same task over and over again

4. A Function by any other name
Often referred to by different names
Function
Function procedure
Sub procedure
Sub
Stored procedure

5. Benefits of Functions Give greater functionality Hide complexity
Promote code re-use
Simplify maintenance

6. Functions gives Greater Functionality
When we want to use the function we simply call it

7. Hides Complexity
Who cares how it works?

8. Simplify Maintenance Create a function
Call it multiple times around our system
Need to make a change
Modify the one function definition
All of the multiple calls benefit from the change

9. Functions Promote Code re-use
A function should perform one task well
Accept enough data via parameters for the task
Return an appropriate value
Organise into class libraries
Allow us to recycle code

10. Functions are used to make…
Event handlers
Public methods in a class
Public properties in a class
Constructors
Test cases
None of the above just a function

11. Function Example

12. Return Values
Two parts of the function work together…

13. Pick the Return Data Type

14. Calling Functions May use function with the assignment operator…
When a function call is completed the flow of code returns to the line where the call was made from!

15. Ignoring the Return Value

16. Void Functions

17. Parameters
This code is not very versatile…
Add parameters…

18. Use the Parameters

19. Calling the Function with Parameters

20. Public Functions to make Methods
Public function in a class file
Becomes a method in an object

21. Public Functions to make Properties - Getters and Setters

22. Using the Debugger with Functions