Programming concepts

Question 1

What does a variable do?

Answer 1

Holds values that can be modified when the program is executed

Question 2

What does a constant do?

Answer 2

Holds values that remain unchanged when a program is executed

Question 3

How do you assign a variable?

Answer 3

Declare the name and data type, then assign a value

Question 4

What are the three main steps to using variables?

Answer 4

Declaration, Assignment, and Initialisation

Question 5

What is declaration?

Answer 5

Creating space in memory for a variable or constant

Question 6

What is assignment?

Answer 6

Setting the contents of the memory space to a value

Question 7

What is initialisation?

Answer 7

Setting the value of a variable before any processing takes place

Question 8

Name the advantages of using constants

Answer 8

You can use the same identifier throughout a program which keeps the program code consistent- making it easy to debug and read, if errors occur changes only need to be made at one point- the initialising of the constant

Question 9

Define an identifier

Answer 9

A name given to any variable, constant, subroutine, or class

Question 10

Why are meaningful identifiers important?

Answer 10

So the purpose of the subroutine is clear to anyone reading your code

Question 11

What are definite loops and how are they implemented? give an example

Answer 11

A set of instructions repeated a certain number of times, implemented by count-controlled loops e.g. for

Question 12

What are indefinite loops and how are they implemented? give an example

Answer 12

A set of instructions that are repeated until a condition is met, implemented by condition control loops e.g. while

Question 13

When does a while loop check its condition?

Answer 13

At the start of each iteration until the condition is met

Question 14

When does a repeat until loop check its condition?

Answer 14

At the end of each iteration until the condition is met

Question 15

What is nested iteration?

Answer 15

When a loop is inside another loop

Question 16

How does nested iteration work?

Answer 16

The inner loop will be executed for all the iterations of the outer loop

Question 17

Define sequence

Answer 17

A series of instructions that a program executes in order, one after another

Question 18

How does selection differ from sequence?

Answer 18

Selection executes a program based on a condition

Question 19

What is nested selection used for?

Answer 19

Implementing branching logic

Question 20

What is branching logic?

Answer 20

If a condition of the main selection block evaluates to true then it leads to sub-conditions which are included inside the main condition

Question 21

What are operands?

Answer 21

The values in calculations to which arithmetic operators are applied

Question 22

`What does DIV do?

Answer 22

Returns ONLY the whole number part of a division, the fractional part is dismissed

Question 23

What does MOD do?

Answer 23

Returns ONLY the remainder of a division

Question 24

What does Round() do?

Answer 24

Rounds up the result of an operation

Question 25

What does Truncate do?

Answer 25

Rounds down the result of an operation

Question 26

What are relation operators used for?

Answer 26

Comparing the values of 2 variables or comparing a given value against a variable

Question 27

What do expressions with relational operators evaluate to?

Answer 27

True or False

Question 28

What are logical operators used for?

Answer 28

Combining multiple factors in a program using logical operators

Question 29

What do expressions with logical operators evaluate to?

Answer 29

True or False

Question 30

When does an AND statement evaluate to True?

Answer 30

When all operands equal True

Question 31

When does an OR statement evaluate to True?

Answer 31

When either of the operands is True

Question 32

When does a NOT statement evaluate to True?

Answer 32

When the operand is equal to False as it reverses its value

Question 33

What is the default order of operations in logical statements(when no brackets are present)?

Answer 33

1. NOT 2. AND 3. OR

Question 34

How are arrays and strings similar?

Answer 34

Each character in a string is indexed but it is immutable( once it's created it can't be changed)

Question 35

Define exception

Answer 35

An exceptional or unexpected event that occurs when a program is running

Question 36

What is exception handling?

Answer 36

The way a program deals with exceptional circumstances without crashing

Question 37

What is a subroutine?

Answer 37

A section of code that can be called by writing the subroutines name in a statement

Question 38

What are the 2 types of subroutine?

Answer 38

Function and procedure

Question 39

What's the difference between a procedure and a function?

Answer 39

Procedures simply execute a set of instructions whereas functions return a value after running

Question 40

Advantages of subroutines

Answer 40

Makes code readable and reusable, shorten programs, subroutines can be tested separately,

Question 41

What does a parameter do?

Answer 41

Defines the data that must be passed into a subroutine when it's called

Question 42

What is an argument?

Answer 42

A piece of data that is passed into a subroutine

Question 43

Which type of subroutine returns a value?

Answer 43

Function

Question 44

What is the scope of a variable?

Answer 44

Where in the program a variable or constant can be accessed

Question 45

Define local variable

Answer 45

A variable that is only accessible within a specific part of a program

Question 46

Do local variables in different subroutines need different names and why?

Answer 46

No, because they're kept in separate

Question 47

Define global variable

Answer 47

A variable that can be accessed anywhere in the program

Question 48

Where are global variables defined?

Answer 48

Outside of the subroutine

Question 49

What's the problem with global variables?

Answer 49

Their values can be altered anywhere so can be changed accidentally

Question 50

if a local variable and global variable have the same, which takes precedence?

Answer 50

The local variable will be taken first but will not override the global variable

Question 51

What is a call stack?

Answer 51

An area of memory allocated to a program to store information about each active subroutine

Question 52

What is an active subroutine?

Answer 52

A subroutine that's been called but hasn't finished executing

Question 53

What does a stack frame store?

Answer 53

The value of any local variables ad the value of any parameters

Question 54

What is a recursive algorithm?

Answer 54

An algorithm that calls itself

Question 55

What's a general case?

Answer 55

A statement that expresses the solution to a problem in terms of a reference to a smaller version of that same problem

Question 56

What's the base case?

Answer 56

The point at which you know the answer to a specific version of a problem

Question 57

What are the criteria for a recursive algorithm, in order?

Answer 57

Define a base case, define the general case

Question 58

Write the general case for any function

Answer 58

sum_to_n(n) = n + sum_to_n(n-1)

Question 59

Write the base case for any function

Answer 59

sum_to_n(1) = 1

Question 60

Are parameter values passed byval or byref in recursive routines?

Answer 60

Byval

Question 61

Advantages of recursion

Answer 61

Natural way to process data structures that are recursive by nature( like trees), Fewer lines of code

Question 62

Disadvantages of recursion

Answer 62

Harder to trace, uses more memory, slower to run