2.2.1 Programming Techniques

Question 1

Name the three programming constructs.

Answer 1

Sequence, branching and iteration.

Question 2

Which two categories of loop is iteration split up into?

Answer 2

• Count-controlled

- Condition-controlled

Question 3

Describe how the branching programming construct works.

Answer 3

A certain block of code is run if specific condition is met, using IF statements.

Question 4

What is recursion?

Answer 4

A programming construct in which a subroutine calls itself during its execution until the stopping condition is met.

Question 5

What is the base case in recursion?

Answer 5

A condition that must be met in order for the recursion to end.

Question 6

State two advantages of recursion.

Answer 6

• Can be represented in fewer lines of code.

- Easier to express some functions recursively than using iteration.

Question 7

State a disadvantage of recursion.

Answer 7

• Inefficient use of memory.
• Danger if stack overflow.
• Difficult to trace.

Question 8

Give two pieces of information that are stored on the call stack.

Answer 8

Two from:

• Parameters
• Return addresses
• Local variables

Question 9

Define scope

Answer 9

The section of the program in which a variable is accessible.

Question 10

Give two advantages of using local variables over global variables.

Answer 10

Two from:

• Less memory is used
• Self-contained so unaffected by code outside of the subroutine
• Take precedence over global variables with the same name

Question 11

What is top-down design?

Answer 11

A technique used to modularise programs in which the problem is continually broken down into sub-problems, until each can be represented as an individual, self-contained module which performs a certain task.

Question 12

State two advantages of a modular design.

Answer 12

Two from:

• Makes a problem easier to understand and approach
• Simpler to divide tasks between a team
• Easier to manage project
• Self-contained modules simplify testing and maintenance
• Greater readability

Question 13

Give another name for top-down design.

Answer 13

Stepwise refinement

Question 14

What is the difference between procedures and functions?

Answer 14

Functions must always return a single value while a procedure does not always have to return a value.

Question 15

What does it mean to pass a parameter to a subroutine by reference?

Answer 15

The address in memory of the parameter is passed to the subroutine so it’s value outside of the subroutine will be updated.

Question 16

State two features of IDEs

Answer 16

Two from:

• Stepping
• Variable watch
• Breakpoint
• Source code editor
• Debugging tools

Question 17

What does IDE stand for?

Answer 17

Integrated Development Environment

Question 18

What is encapsulation in object-oriented programming?

Answer 18

When attributes are declared as private so can only be accessed and edited by public methods.

Question 19

Describe the purpose of encapsulation in object-oriented programming.

Answer 19

Program complexity is reduced by protecting data from being accidentally edited by other parts of the program.