Concepts - Variables, Iteration, Functions

Question 1

What is a variable

Answer 1

Variables are storage areas within our programs. If we need to use data later on, it MUST be stored in a variable. Variables can be changed, so we can replace the data being stored at anytime.

Question 2

What is a constant

Answer 2

Constants are like variable but CANNOT be changed after being set up. Python does not cater for Constants, so to indicate a Constant we use ALL CAPS. This tells the programmer to not change the value in this variable.

Question 3

What is Declaration

Answer 3

Declaration or declaring a variable means to create the variable.

Question 4

What is Assignment

Answer 4

Assignment means to add the data to the variable.

Question 5

What is Iteration

Answer 5

Iteration is performing loops or repeating sequences of code.

Question 6

What are the 2 types of iteration

Answer 6

There are 2 types of iteration:
Indefinite Iteration (condition controlled)
This is WHILE … ENDWHILE or REPEAT…UNTIL
Definite Iteration (count controlled)
FOR…ENDFOR

Question 7

What are 2 properties of a ‘while … endwhile’ loop

Answer 7

2 properties:
Boolean Expression
Test the expression at the start of the loop.

num ← RANDOM NUMBER (1,20)
guess ← 0
WHILE guess < > num
	OUTPUT “Enter a Number”
	guess ←  INPUT
ENDWHILE

Question 8

What are 2 properties of a ‘repeat … until’ loop

Answer 8

Similar to WHILE
2 properties:
Boolean Expression
Test the expression at the END of the loop.

num ← RANDOM NUMBER (1,20)
REPEAT
	OUTPUT “Enter a Number”
	guess ←  INPUT
UNTIL (guess == num)

Question 9

What is a ‘for … end for’ loop used for?

Answer 9

Used when you know how many times you are going to repeat something.
Uses Counting(stepping) Variable which could be integers or value from list.
FOR count ← 1 TO 12
PRINT count
ENDFOR

Question 10

What is Nested Iteration

Answer 10

Loops within Loops:
FOR count ← 1 TO 10
	FOR  times ← 1 TO 10
		PRINT count * times
	ENDFOR
ENDFOR

Question 11

What is a subroutine?

Answer 11

Subroutines can be functions or procedures. They are blocks of code that can be referenced and used anywhere in the program.

Question 12

Define Built-in functions

Answer 12

These are functions that are pre-defined for the language you are using. ord() chr() len() are examples in python

Question 13

Define Parameters

Answer 13

These are the variables that are created to bring data into a function or procedure. AKA arguments.
Found in brackets beside subroutine name and if multiple parameters, they are separated by a comma.

Question 14

Define Local Variable’s

Answer 14

These are variables that are known only in the subroutine in which they are created or paramatised.

Question 15

Define Global Variables

Answer 15

Global Variables

These are variables that are known throughout the program by all parts