slr23 - programming constructs

Question 1

Describe sequence

Answer 1

The default mode for code to work in: executing instruction one after another

Question 2

Describe selection

Answer 2

Allows a program to change direction depending on the outcome of a condition

Question 3

Describe iteration

Answer 3

Also called looping: enables us to repeat lines of code

Question 4

What is recursion

Answer 4

When a subroutine calls itself from within its own subroutine

Question 5

What are the features of recursion

Answer 5

Contains a stopping condition
For any value other than the stopping condition the subroutine should stop itself
The stopping condition should be reachable in a finite amount of times

Question 6

What causes a stack overflow in relation to recursion

Answer 6

When a recursive function calls itself indefinitely

Question 7

When is recursion used

Answer 7

Tree traversal algorithems

Question 8

What is the scope of a variable

Answer 8

From where in the program it can be accessed from

Question 9

What is a local variable

Answer 9

A var that can only be accessed from inside of a specific subroutine

Question 10

What is a global variable

Answer 10

A var that can be accessed from anywhere in the program

Question 11

Why is it sometimes better to use local variables

Answer 11

In large programs global vars can be confusing
Global vars are not deleted after they have been used therefore they take up more space in memory

Question 12

What is a function

Answer 12

A block of code that:
Takes in parameters
Performs a set task
returns a value

Question 13

What is a procedure

Answer 13

A block of code that:
Takes in parameters
Performs a set task

Question 14

What are parameters

Answer 14

Values that are passed into a function

Question 15

Passing by reference

Answer 15

References the location in memory
This means that the value can be changed

Question 16

Describe passing by value

Answer 16

Creates a copy of the variable
The original value cannot change