A-LevelComputer ScienceAlgorithm design and problem-solving9618/21 · May/June 2022 · Q56 Marks

Each line of a text file contains data organised into fixed-length fields as shown: <Field 1><Field 2><Field 3> An algorithm is required to search for the first instance of a given value of Field 2 and, if found, to output the corresponding values for Field 1 and Field 3. Describe the algorithm needed. Do not include pseudocode statements in your answer.

(a)Each line of a text file contains data organised into fixed-length fields as shown: <Field 1><Field 2><Field 3> An algorithm is required to search for the first instance of a given value of Field 2 and, if found, to output the corresponding values for Field 1 and Field 3. Describe the algorithm needed. Do not include pseudocode statements in your answer.[6]

Mark scheme

Marking points from the official mark scheme (May/June 2022). The mark or mark type is shown in brackets.

[6] (a) One mark per point to Max 6
[6] (a) 1 Open file in read mode
[6] (a) 2 Set up a conditional loop, repeating until the value is found or the EOF() is reached
[6] (a) 3 Read a line from the file in a loop
[6] (a) 4 Extract Field 2
[6] (a) 5 Description of how Field 2 could be extracted e.g. using substring function and lengths of Field 1 and Field 2
[6] (a) 6 Compare extracted field with search value
[6] (a) 7 If search value found, extract Field 1and Field 3 and output them
[6] (a) 8 Close the file after loop has finished

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