A procedure LastLines() will: • take the name of a text file as a parameter • output the last three lines from that file, in the same order as they appear in the file. Note: • Use local variables LineX, LineY and LineZ to store the three lines from the file. • You may assume the file exists and contains at least three lines. Write pseudocode for the procedure LastLines().

Mark scheme

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

1. [6] Marks as follows to Max 6:
2. 1 Procedure heading (including parameter) and ending
3. 2 Declaration of local variables for three lines AND File OPEN in READ mode AND CLOSE
4. 3 Loop until EOF(ThisFile)
5. 4 Read line from file... in a loop
6. 5 Attempt at a shuffle... in a loop
7. 6 Correctly shuffle LineX, LineY and LineZ in a loop
8. 7 OUTPUT the three lines in correct sequence, following reasonable attempt
9. Alternative (using two loops):
10. [6] Marks as follows to Max 6:
11. 1 Procedure heading (including parameter) and ending
12. 2 Declaration of local variables for three lines AND (at least one) File OPEN in READ mode AND CLOSE
13. 3 Loop until EOF(ThisFile)
14. 4 Read line from file and increment Count in a loop
15. 5 Two separate loops, closing and re-opening the file between loops
16. 6 Read Count - 3 lines from the file
17. 7 OUTPUT the last three lines in correct sequence, following reasonable attempt
18. [3] One mark per point to Max 3:
19. 1 Change the procedure header to include a (numeric) parameter (as well as the filename)
20. 2 Replace LineX, Y and Z with an array
21. 3 Amend shuffle mechanism
22. 4 Use new parameter to determine first line to output
23. 5 Output the lines in a loop
24. Alternative 'two loop' solution to Max 3:
25. 1 Change the procedure header to include a numeric parameter (as well as the filename)
26. 2 A loop to count the total number of lines in the file
27. 3 Ref use of single variable rather than LineX, LineY and LineZ
28. 4 Close and re-open the file
29. 5 Use the new parameter value to determine first line to output
30. 6 Output the lines in a loop