2.2 - Programming Fundamentals

Variable

A value that can change while the program is running

Constant

A value that remains fixed and cannot change while the program is running

Assignment

Where you give/assign a value to a variable or constant using the = symbol

Operator

Used on variables and constants to perform mathematical operations

Casting

Converting a variable form one data type to another

Integer

A whole number

Real

A decimal number

Character

A single alphanumeric character

String

Multiple characters

Boolean

True/False values

Input casting

Can be assigned from a string to a number variable

Output statement

Used to output or print to the screen

Sequencing

Executing one instruction after another

Selection

Branching a program based on a condition (if/else)

Iteration

Looping/repeating sections of code (for/while)

Addition

Adding two values using +

Subtraction

Subtracting two values using -

Multiplication

Multiplying two values using *

Division

Dividing two values using /

Exponential

‘To the power of’ using ^

Modulus

‘How many whole numbers are left over after dividing two numbers’ using MOD eg: 7MOD2 = 1 (3 remainder 1)

Integer division

‘How many times a whole number fits into another number using’ DIV eg: 7DIV2 = 3 (3 remainder 1)

Is equal to

==

Is not equal to

!=

Less than

<

Less than or equal to

<=

Greater than

>

Greater than or equal to

>=

String manipulation

The act of manipulating, extracting or changing characters in a string variable

Length

string.length eg: if string == hello, length == 5

Ustring

string.upper eg: if string == hello, string becomes HELLO

Lstring

string.lower eg: if string == Hello, string becomes hello

Substrings

string.substring(starting position, number of characters)

Eg: if string == buenos dias, string.substring(2,3), prints characters ‘eno’

String shift

Shifting a string left or right eg: string.left(3), shifts characters left by 3 places

ASCII characters in strings

ASC(“A”), returns ASCII value of “A”

CHR(65), returns character with ASCII value of 65

SELECT

Selects field to be returned

FROM

Which table in the database

WHERE

Records meet a condition

Array

A variable which can continue more than one data item eg: a list of names

Index

A way of finding a specific item in an array eg: food[0,0] == “apple”

Subprogram

Program within a program

Procedure

Carry out a task and don’t return values

Functions

Carry out a task and return a value

Advantages of subprograms

• Easier to write and debug

• Easier to test and put into the main body

Random number generation

Random(1,6), generates a random number between 1 and 6 inclusive