Algorithm Constructs

Algorithm Constructs

1. Sequence

   • number of instructions that are processed one after the other.
     • DECLARE count SET count TO 1 OUTPUT the value of count

2. Assignment

   • used to store the value of an expression into a variable.
     • DECLARE studentName SET studentName TO Bob

3. Selection and Condition

   • uses a condition to select, or determine, the next line of the program that is to be executed.
     • CALCULATE totalCost IF (totalCost > $10) THEN OUTPUT   'no delivery charge' ELSE OUTPUT  '$5 delivery charge' ENDIF OUTPUT  'thankyou'

4. Iteration (FOR Loop)

   • is used when it is known exactly how many times to go round the loop
     • DECLARE count Set TO 0 FOR count = 1 to 10 OUTPUT count END FOR OUTPUT ‘finished’

5. Iteration (WHILE Loop)

   • used to repeat while a condition is true or false.
     • DECLARE count SET count TO 0 WHILE (there are items in a pile) ADD 1 TO count  END WHILE OUTPUT the number of items

6. Modularisation

   • used to reduce the complexity of a system by deconstructing it into independent units or modules. We use the term "function" as that is what they are called in most of the popular programming languages of today. Functions are important because they allow us to take large complicated programs and divide them into smaller manageable pieces that are more easily maintained.
     • FUNCTION delivery_charge CALCULATE totalCost IF (totalCost > $10)  THEN OUTPUT  ‘no delivery charge’ ELSE OUTPUT  ‘$5 delivery charge’ ENDIF OUTPUT  ‘thankyou’ END FUNCTION