A-LevelComputer ScienceProgramming9618/23 · May/June 2024 · Q27 Marks
A program uses a global 1D array of type string and a text file. An algorithm that forms part of the program is expressed as follows: • copy the first line from the file into the first element of the array • copy the second line from the file into the second element of the array • continue until all lines in the file have been copied into the array. Stepwise refinement is applied to the algorithm. Outline five steps for this algorithm that could be used to produce pseudocode. Assume there are more elements in the array than lines in the file. Do not use pseudocode statements in your answer.
- (a)Outline five steps for this algorithm that could be used to produce pseudocode. Assume there are more elements in the array than lines in the file. Do not use pseudocode statements in your answer. Step 1 Step 2 Step 3 Step 4 Step 5[5]
- (b)Sequence is one programming construct. Identify one other programming construct that will be required when the algorithm from part (a) is converted into pseudocode and explain its use. Construct Use[2]
Mark scheme
Marking points from the official mark scheme (May/June 2024). The mark or mark type is shown in brackets.
- [1] (a) Open the file (in read mode and subsequently close)
- [1] (a) Initialise an index variable (to 1 // 0)
- [1] (a) Repeat (the next three steps) until the end of file is reached
- [1] (a) Read a line from the file (into a string variable)
- [1] (a) Store the line / variable in the array at the index
- [1] (a) Increment the index in a loop
- [1] (b) Construct: a conditional loop
- [1] (b) Use: To keep repeating until the end of the file is reached
- [1] (b) ALTERNATIVE: Construct: a selection statement
- [1] (b) Use: To test / check the value returned by the EOF () function
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