1.2.4 types of programming language

• series of statements (instructions) that are executed one after another

• accept input • process data • produce output

• sequence • selection • iteration

• executing instructions one after another

• allows a program to branch and follow a different direction depending on outcome of a certain condition

• repeating / looping sections of code

WHILE True

• count-controlled loop • used when required number of iterations is known ahead of execution

• condition-controlled loop • used when required number of iterations isn’t known because the variable used to determine when the iteration ends is changing within the iteration itself

• alternative to WHILE where the code executes at least once before condition is checked

• WHILE loop, condition checked at start (if condition met, we may never execute the following lines of code in WHILE loop) • DO… UNTIL loop always executes code once before checking exit condition at end

• control flow of program

The path that a program follows as it runs from start to finish.

• process of putting one statement inside another • this can be achieved through both iteration and selection statements

• pointer to a memory location that holds a value. It is defined by a name/label. CAN BE CHANGED WHILE THE PROGRAM IS RUNNING.

• a memory location that holds a value. It is defined by a name/label CANNOT BE CHANGED WHILE THE PROGRAM IS RUNNING

• block of code given a unique, identifiable name within a program

• break down larger problem into series of smaller + more manageable problems • this makes code easier to write, debug and test • creates reusable components

• Both are blocks of code (provide structure to code) which carry out a set task • they are defined under a name which can be called and run simply by stating name of the function / procedure. • Functions return values whereas procedures only execute commands. • functions also create reusable program components

• methods

• converting value into a different data type • e.g string to integer using command int

+ (addition) - (subtraction) * (multiplication) / (division) ^ or ** (exponentiation) MOD or % (remainder) DIV or // (e.g 7 DIV 2 = 3, its the nearest integer answer)

== (equal to) != (not equal to) < (less than) <= (less than or equal to) > (greater than) >= (greater than or equal to)

AND / OR / NOT / XOR