A-LevelComputer ScienceProgramming9618/23 · May/June 2024 · Q56 Marks
A program is being designed in pseudocode. The program contains the following declaration: DECLARE Data : ARRAY[1:1000] OF STRING A procedure ArrayInitialise() is written to initialise the values in the array: PROCEDURE ArrayInitialise(Label : STRING) DECLARE Index : INTEGER Index ← 1 WHILE Index <= 1000 CASE OF (Index MOD 2) 0 : Data[Index] ← FormatA(Label) Index ← Index + 1 1 : Data[Index] ← FormatB(Label) Index ← Index + 1 ENDCASE ENDWHILE ENDPROCEDURE Functions FormatA() and FormatB() apply fixed format case changes to the parameter string.
- (a)The design of the procedure does not use the most appropriate loop construct. Suggest a more appropriate construct that could be used and explain your choice. Construct Explanation[2]
- (b)The algorithm calls one of the functions FormatA() and FormatB() each time within the loop. Explain why this is not efficient and suggest a more efficient solution.[4]
Mark scheme
Marking points from the official mark scheme (May/June 2024). The mark or mark type is shown in brackets.
- [1] (a) Construct: Count-controlled loop
- [1] (a) Explanation: the number of iterations is known
- [1] (b) The functions will return the same value every time they are called
- [1] (b) ... because Label / the parameter value does not change within the loop
- [1] (b) Assign FormatA(Label) and FormatB(Label) to two (local) variables before the loop
- [1] (b) Use the (new) variables in place of the function calls / in the loop // Replace the references to FormatA() and FormatB() in the CASE clauses with the new variable names
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