IGCSE Computer Science Paper 2 Definitions Worksheet: 8.1c Procedures and Functions (Modules 409–418)
Name:
Date:
Class:
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Key terms
Write what each term means, in your own words.
1
CALL Name(value1, value2)
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Define then call
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FUNCTION GetPi RETURNS REAL
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RETURN
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FUNCTION SumSquare(Number1:INTEGER, Number2:INTEGER) RETURNS INTEGER
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RETURNS
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SumSquare(10, 20) + 1
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OUTPUT SumSquare(10, 20)
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Total ← SumSquare(3, 4)
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IF IsEven(Number) THEN
Answer Key
IGCSE Computer Science Paper 2 · Modules 409–418 · Student wording will vary for definitions
1CALL Name(value1, value2) — Each value in a call must match its parameter in number, order and data type, so a STRING cannot go to an INTEGER parameter and values cannot be swapped or left out.
2Define then call — Write procedures and functions at the start of the code, before the main program. The main program comes after and holds the CALL statements and function calls that use them.
3FUNCTION GetPi RETURNS REAL — Starts a function with no parameters: the name has no brackets, RETURNS gives the data type of the value sent back, and ENDFUNCTION closes the function.
4RETURN — RETURN followed by a value or expression sends that value back to where the function was called, e.g. RETURN Number1 * Number1. It also ends the function.
5FUNCTION SumSquare(Number1:INTEGER, Number2:INTEGER) RETURNS INTEGER — A function header lists each parameter in brackets as name:TYPE, then RETURNS and the return type. The body uses the parameters in a RETURN expression and ends with ENDFUNCTION.
6RETURNS — Keyword in a function header, followed by a data type such as INTEGER, REAL, STRING or BOOLEAN. The value sent back by RETURN must be of that same type.
7SumSquare(10, 20) + 1 — A function call is written inside an expression, with no CALL keyword. The returned value replaces the call, then the rest of the expression is worked out.
8OUTPUT SumSquare(10, 20) — Puts a function call inside OUTPUT. The function runs first, then the value it RETURNs is displayed. Text can be added: OUTPUT "Sum = ", SumSquare(10, 20).
9Total ← SumSquare(3, 4) — The function runs, and the value it returns is stored in the variable on the left of the arrow. You can use that variable later. Its type must match the function's return type.
10IF IsEven(Number) THEN — A function that RETURNS a BOOLEAN can be called straight in an IF or WHILE condition. The call gives TRUE or FALSE, so no comparison is needed.