A computer shop assembles desktop computers, using items bought from several suppliers. A text file Stock.txt contains information about each item. Information for each item is stored as a single line in the Stock.txt file in the format: <ItemNum><SupplierCode><Description> Item information is as follows: | | Format | Comment | |:---|:---|:---| | ItemNum | 4 numeric characters | unique number for each item in the range "0001” to "5999" inclusive | | SupplierCode | 3 alphabetic characters | code to identify the supplier of the item | | Description | a string | a minimum of 12 characters | The file is organised in ascending order of ItemNum and does not contain all possible values in the range. The programmer has defined the first program module as follows: | Module | Description | |:---|:---| | ChangeSupp() | • called with two parameters Code1 and Code2 of type string that represent valid supplier codes | • creates a new file NewStock.txt from the contents of the file Stock.txt where any reference to Code1 is replaced by Code2 | • returns a count of the number of items that have had their supplier code changed |

Mark scheme

Marking points from the official mark scheme (May/June 2023). The mark or mark type is shown in brackets.

1. [8] FUNCTION ChangeSupp(Code1, Code2 : STRING) RETURNS INTEGER
2. [8] DECLARE Count : INTEGER
3. [8] DECLARE ThisLine, ThisCode : STRING
4. [8] OPENFILE "Stock.txt" FOR READ
5. [8] OPENFILE "NewStock.txt" FOR WRITE
6. [8] Count ← 0
7. [8] WHILE NOT EOF("Stock.txt")
8. [8] READFILE("Stock.txt ", ThisLine) // brackets optional
9. [8] ThisCode ← MID(ThisLine, 5, 3)
10. [8] IF ThisCode = Code1 THEN
11. [8] ThisLine ← LEFT(ThisLine, 4) & Code2
12. [8] & RIGHT(ThisLine, LENGTH(ThisLine) - 7)
13. [8] Count ← Count + 1
14. [8] ENDIF
15. [8] WRITEFILE("NewStock.txt", ThisLine) // brackets optional
16. [8] ENDWHILE
17. [8] CLOSEFILE "NewStock.txt"
18. [8] CLOSEFILE "Stock.txt"
19. [8] RETURN Count
20. [8] ENDFUNCTION
21. [8] MP1 Open both files, in correct modes, and subsequently close
22. [8] MP2 Conditional loop until EOF (“Stock.txt")
23. [8] MP3 Read a line from Stock.txt AND extract ThisCode in a loop
24. [8] MP4 Test ThisCode = Code1 AND if true, increment Count (must have been Initialised) in a loop
25. [8] MP5 Update ThisLine using substring functions and '&' in a loop
26. [8] MP6 completely correct update of ThisLine in a loop
27. [8] MP7 Write ThisLine to NewStock.txt in a loop
28. [8] MP8 Return count after loop
29. [6] PROCEDURE Report_1(Supp : STRING)
30. [6] DECLARE Count : INTEGER
31. [6] DECLARE ThisItemNum, ThisDesc, ThisLine, ThisCode : STRING
32. [6] Count ← 0
33. [6] OPENFILE "Stock.txt" FOR READ
34. [6] OUTPUT "Report for Supplier:" & Supp
35. [6] OUTPUT "" //Blank line as per example
36. [6] OUTPUT "Item Description"
37. [6] OUTPUT "" //Blank line as per example
38. [6] WHILE NOT EOF("Stock.txt")
39. [6] READFILE("Stock.txt", ThisLine)
40. [6] ThisCode ← Mid(ThisLine, 5, 3)
41. [6] IF ThisCode = Supp THEN
42. [6] ThisItemNum ← LEFT(ThisLine, 4)
43. [6] ThisDesc ← RIGHT(ThisLine, LENGTH(ThisLine) - 7)
44. [6] OUTPUT ThisItem & " " & ThisDesc
45. [6] Count ← Count + 1
46. [6] ENDIF
47. [6] ENDWHILE
48. [6] CLOSEFILE "Stock.txt"
49. [6] OUTPUT "" //Blank line as per example
50. [6] OUTPUT "Number of items listed: ", Count
51. [6] ENDPROCEDURE
52. [6] MP1 Output report header (blank lines optional) – Must contain the parameter code
53. [6] MP2 Conditional loop until EOF("Stock.txt")
54. [6] MP3 Read a line from Stock.txt AND extract SupplierCode in a loop
55. [6] MP4 Test if SupplierCode = Supp then increment count (must have been Initialised)
56. [6] MP5 Extract AND output item and description in a loop
57. [6] MP6 Output the final line with count
58. [2] Max 2 marks
59. [2] MP1 Must 'calculate' the count before any item + description output / after the file is read once
60. [2] MP2 Lines to be output have to be stored ...
61. [2] MP3 The file has to be read twice
62. [3] One mark per point:
63. [3] MP1 Loop through the file calculating the count
64. [3] MP2 Save 'selected' items in an array
65. [3] MP3 (After all lines have been read), output the header lines / count
66. [3] MP4 Loop through the array to output each array element