IGCSE Computer Science Paper 2 Definitions Worksheet: 7b Decomposition and Sub-systems (Modules 123–134)
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Key terms
Write what each term means, in your own words.
1
Subroutine symbol
2
main flowchart
3
KEYWORDS IN CAPITALS
4
Total ← 0
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INPUT Name
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IF THEN ELSE ENDIF
7
FOR Count ← 1 TO 10
8
WHILE ... DO ... ENDWHILE
9
PROCEDURE Name() ... ENDPROCEDURE
10
FUNCTION Name(Param : TYPE) RETURNS TYPE
Answer Key
IGCSE Computer Science Paper 2 · Modules 123–134 · Student wording will vary for definitions
1Subroutine symbol — A rectangle with double side lines. It stands for a call to a subroutine whose steps are drawn in a separate flowchart, which keeps the main flowchart short.
2main flowchart — A flowchart that calls each sub-problem from the structure diagram with a subroutine symbol. Each sub-problem then gets its own separate flowchart.
3KEYWORDS IN CAPITALS — Cambridge pseudocode writes keywords like INPUT, OUTPUT and IF in capital letters, puts one statement on each line, and indents the statements inside IF and loops.
4Total ← 0 — The ← symbol is assignment: it stores the value on its right in the variable on its left. Total ← 0 sets Total to 0. Total ← Total + Score adds Score to Total.
5INPUT Name — INPUT reads a value from the user into the variable Name. OUTPUT displays a value or message on screen, such as OUTPUT "Hello" or OUTPUT Name.
6IF THEN ELSE ENDIF — Runs the indented lines after THEN if the condition is true, otherwise runs the ELSE lines. ENDIF closes the construct and sits at the same indent as IF. ELSE is optional.
7FOR Count ← 1 TO 10 — A count-controlled loop that repeats the indented statements a fixed number of times, with Count going from 1 to 10. NEXT Count closes the loop and moves Count up by 1.
8WHILE ... DO ... ENDWHILE — A loop that tests its condition before each repeat, so it may run 0 times. REPEAT ... UNTIL runs the body first and tests after, so it always runs at least once.
9PROCEDURE Name() ... ENDPROCEDURE — Defines a named block of pseudocode for one sub-problem. It does not return a value. The block only runs when you write CALL Name() in the main program.
10FUNCTION Name(Param : TYPE) RETURNS TYPE — Starts a function that takes a typed parameter and RETURNS a value of the stated type. RETURN sends the value back, ENDFUNCTION closes it, and you can call it inside an expression.