User Defined Functions

Question 1

What is a subprogram?

Answer 1

Groups of code that break large programs down into smaller parts. In processing, these are called functions (methods in Java and C#)

Question 2

What do functions allow programmers to do?

Answer 2

• write a large program piece by piece
• many programmers can work on separate parts of the program
• standard libraries of subprograms can be used by many people
• functions with parameters allow variation in the function outcome

Question 3

What are functions?

Answer 3

Blocks of code which encapsulate some task into a black box or module

Question 4

What things make up all functions?

Answer 4

• a name
• some data items they accept, with specific types (parameters)
• a type of data item that they give back as a result (or void)

Question 5

What is the signature of the function?

Answer 5

The name and the types
eg. float getPercent(int, int)

Question 6

What happens of values passed in as parameters?

Answer 6

They are copied and stored in the function’s local variable.

Question 7

What happens if the you change the value of the local variable in the function?

Answer 7

The values passed will not change

Question 8

What happens to local variables after a function is finished executing?

Answer 8

They disappear

Question 9

How many return types can a function have?

Answer 9

one or none

Question 10

What happens when the return statement is executed?

Answer 10

The function is exited and optionally returns the value from it.

Question 11

Are return statements required?

Answer 11

If the return type is not void, then yes. Otherwise, they are optional. It is best practice to only have one return statement

Question 12

What happens when you pass a String into a function?

Answer 12

The address stored in the original String variable is copied into the local variable. This means that any changes made to the String will be reflected outside of the function

Question 13

What is the header?

Answer 13

The first line of code of an actual function definition. Unlike the signature, which is an abstraction of the header and is only used to match function calls to functions

Question 14

What is function overloading?

Answer 14

Defining multiple functions with the same name but different parameter lists (two functions with the same name must have different signatures)

Question 15

Can you use variables of the same name outside of a function?

Answer 15

Yes. Parameters and variables defined in a function become local to that function

Question 16

What are stand-alone functions?

Answer 16

Functions that don’t change globals. All data comes in through parameters and goes out through return. These are good because you don’t have to worry about side-effects

Question 17

What are function side-effects?

Answer 17

Usually when a function changes non-final global variables, it might have some unexpected outcomes