Psuedocode<3

• The consistent style of pseudo-code used in assessments ensures that students will understand the syntax with enough preparation
• Students are directed to ensure their code is clear, consistent, and unambiguous when answering questions or describing algorithms written in pseudo-code
• The resource on pseudo-code may be updated as required and the latest version will always be available on the website
• The names of constants in pseudo-code will always be written in capitals
• Arithmetic operations

  • +
  • -
  • *
  • /
  • DIV
  • MOD
• Relational operators

  • <
  • >
  • =
  • !=
  • <=
  • >=
  • AND
  • OR
  • NOT
• Variable assignment


  1. a ← 3

  2. b ← a + 1

  3. c ← 'Hello'
• Constant assignment

  1. CONSTANT PI ← 3.141

  2. CONSTANT CLASS_SIZE ← 23
• Indefinite (condition controlled) iteration - REPEAT-UNTIL


  1. REPEAT

  2. UNTIL BoolExp
• Indefinite (condition controlled) iteration - WHILE-ENDWHILE

  1. WHILE

  2. ENDWHILE
• Indefinite (condition controlled) iteration

  1. REPEAT-UNTIL (repeat the statements until the Boolean expression is True)

  2. REPEAT...UNTIL BoolExp

  3. WHILE-ENDWHILE (while the Boolean expression is True, repeat the statements)
• REPEAT-UNTIL

  Repeat the statements until the Boolean expression is True
• WHILE-ENDWHILE

  While the Boolean expression is True, repeat the statements
• Definite (count controlled) iteration

  1. FOR-TO-[STEP]-ENDFOR (If STEP IntExp is missing it is considered to be 1)

  2. FOR Identifier ← IntExp TO IntExp [STEP IntExp]...ENDFOR

  3. FOR-IN-ENDFOR (repeat the statements the number of times that there are characters in a string)
• FOR-TO-[STEP]-ENDFOR


  If STEP IntExp is missing it is considered to be 1
• FOR-IN-ENDFOR


  Repeat the statements the number of times that there are characters in a string
• Selection

  1. IF-THEN-ENDIF (execute the statements only if the Boolean expression is True)

  2. IF-THEN-ELSE-ENDIF (execute the statements following the THEN if the Boolean expression is True, otherwise execute the statements following the ELSE)

  3. NESTED IF-THEN-ELSE ENDIF (use nested versions of the above to create more complex conditions)
• IF-THEN-ENDIF


  Execute the statements only if the Boolean expression is True
• IF-THEN-ELSE-ENDIF


  Execute the statements following the THEN if the Boolean expression is True, otherwise execute the statements following the ELSE
• NESTED IF-THEN-ELSE ENDIF


  Use nested versions of the above to create more complex conditions
• IF (a MOD 4) = 2 THEN OUTPUT 'leaves a remainder of 2' ELSE OUTPUT 'leaves a remainder of 3' ENDIF
• IF-THEN-ELSE IF ENDIF removes the need for multiple indentation levels
• Assignment


  Identifier ← [Exp, … ,Exp]
• primes

  • 2
  • 3
  • 5
  • 7
  • 11
  • 13
• Accessing an element


  Identifier[IntExp]
• Updating an element

  Identifier[IntExp] ← Exp
• Accessing an element in a two-dimensional array


  Identifier[IntExp][IntExp]
• table


  • [[1, 2],[2, 4],[3, 6],[4, 8]]
• Array length

  LEN(Identifier)
• FOR-IN-ENDFOR


  FOR Identifier IN array # statements here ENDFOR
• Array items cannot be modified using FOR-IN-ENDFOR method
• Record declaration

  RECORD Record_identifier field1 : <data type> field2 : <data type> … ENDRECORD
• Car

  • make : String model : String reg : String price : Real noOfDoors : Integer
• Variable Instantiation

  varName ← Record_identifier(value1, value2, …)
• Assigning a value to a field in a record

  varName.field ← Exp
• Accessing values of fields within records

  varName.field
• Subroutine definition

  SUBROUTINE Identifier(parameters) # statements here ENDSUBROUTINE
• showAdd

  • a, b
• sayHi

  • 
    
• Subroutines

  • Contain RETURN keyword are functions, those without are procedures