Sub-programs

Question 1

Modularity

Answer 1

The concept of breaking a large program or problem down into smaller chunks

Question 2

Subprogram

Answer 2

Self-contained section of code that performs a task

Question 3

Difference between procedures and functions

Answer 3

Procedures do not return a value. Functions do return a value.

Question 4

Parameter

Answer 4

An item that is passed into a function or procedure

Question 5

Argument

Answer 5

The value passed into a parameter

Question 6

Benefits of sub programs

Answer 6

• Allows several programmers to work on an individual program at the same time
• Code is easier to debug, update, modify and understand
• Can be reused to solve similar problems

Question 7

Parameter passing by value

Answer 7

Value created for a subroutine being called is a copy of the original.
The parameter is held in a separate memory location therefore is only available to that subroutine.
Copy is now a local variable of that subroutine.

Question 8

Parameter passing by reference

Answer 8

A pointer that contains the memory address of the original variable is created.
Any change to that value from within the called subroutine will also affect the value of the original variable.

Question 9

Difference between passing by val and ref

Answer 9

By ref:
- The location (in memory) of the data is used. Any changes are retained after the procedure or function has been completed.

By val:
- A local copy of the data is use. This is discarded when the subprogram exits.