Programming techniques

Question 1

Name the 3 programming constructs

Answer 1

• Sequence
• Branching
• Iteration

Question 2

Which 2 categories of loop is iteration split up into?

Answer 2

• Count-controlled

- Condition-controlled

Question 3

Describe how the branching program construct works

Answer 3

A certain block of code is run if a 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 2 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 of stack overflow
• Difficult to trace

Question 8

Give 2 pieces of information that are stored on the call stack

Answer 8

• Parameters
• Return addresses
• Local variables

Question 9

Define scope

Answer 9

The section of the program in which a variable is accessible

Question 10

What is meant by a local variable?

Answer 10

• Limited scope
• Set or declared inside a function or other subprogram
• Can only be accessed from within that subprogram

Question 11

What is meant by a global variable?

Answer 11

• Can be accessed throughout a program

- Declared or set outside any functions or subprograms

Question 12

Give 2 advantages of using local variables over global variables

Answer 12

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

Question 13

What is top-down design?

Answer 13

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

Question 14

Give another name for top-down design

Answer 14

Stepwide refinement

Question 15

State 2 advantages of a modular design

Answer 15

• 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 reusability

Question 16

What is the difference between procedures and functions?

Answer 16

• Functions must always return a single value

- Procedure does not always have to return a value

Question 17

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

Answer 17

• Address of the variable is passed to the subprogram

- If a variable is changed by the subprogram, it stays changed

Question 18

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

Answer 18

• When you pass a parameter a copy is made for the subprogram
• Changing the value in the subprogram does not change the original value

Question 19

State 2 features of IDEs

Answer 19

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

Question 20

What is encapsulation in object-oriented programming?

Answer 20

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

Question 21

Describe the purpose of encapsulation in object-oriented programming

Answer 21

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

Question 22

What is meant by inheritance?

Answer 22

Allows a class to inherit all methods and attributes of a parent class (as well as having its own)

Question 23

What is meant by polymorphism?

Answer 23

The ability to use the same code to process different objects according to their type