A teacher is designing a program to perform simple syntax checks on programs written by students. Student programs are submitted as text files, which are known as project files. A project file may contain blank lines. The teacher has defined the first program module as follows: Module CheckFile() Description • takes the name of an existing project file as a parameter of type string • returns TRUE if the file is valid (it contains at least 10 non-blank lines), otherwise returns FALSE

Mark scheme

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

1. [1] (a) Function heading and ending including parameter and return type
2. [1] (a) Declaration and initialisation of local Integer for Count
3. [1] (a) OPEN in READ mode and CLOSE
4. [1] (a) Conditional loop until EOF ()
5. [1] (a) Read a line in a loop
6. [1] (a) If non-blank, increment count in a loop
7. [1] (a) Terminate loop when 10 non-blank lines have been read
8. [1] (a) Return Boolean in both cases
9. FUNCTION CheckFile(ThisFile : STRING) RETURNS BOOLEAN DECLARE Valid : BOOLEAN DECLARE ThisLine : STRING DECLARE Count : INTEGER Count <- 0 Valid <- FALSE OPEN ThisFile FOR READ WHILE NOT EOF(ThisFile) AND Valid = FALSE READFILE ThisFile, ThisLine IF ThisLine <> "" THEN Count <- Count + 1 IF Count > 9 THEN Valid <- TRUE ENDIF ENDIF ENDWHILE CLOSEFILE ThisFile RETURN Valid ENDFUNCTION
10. [1] (b) Module name, at least one parameter in brackets and one parameter correct
11. [1] (b) Completely correct statement
12. CALL CountErrors("Jim01Prog.txt", 20)
13. [1] (c) Procedure heading and ending including parameters
14. [1] (c) Declaration and initialisation of local Integer value for ErrCount
15. [1] (c) Use of CheckFile(),output message and terminate if it returns FALSE
16. [1] (c) Conditional loop until EOF ()
17. [1] (c) ...or ErrCount > MaxErrors
18. [1] (c) Read line and use as parameter to CheckLine() in a loop
19. [1] (c) Test return value and increment ErrCount if non-zero in a loop
20. [1] (c) Output either message once only as appropriate
21. PROCEDURE CountErrors(ThisFile : STRING, MaxErrors : INTEGER) DECLARE ErrCount, ThisError : INTEGER DECLARE ThisLine : STRING ErrCount <- 0 IF CheckFile(ThisFile) = FALSE THEN OUTPUT "That program file is not valid" ELSE OPEN ThisFile FOR READ REPEAT READFILE ThisFile, ThisLine ThisError <- CheckLine(ThisLine) IF ThisError <> 0 THEN ErrCount <- ErrCount + 1 ENDIF UNTIL ErrCount > MaxErrors OR EOF(ThisFile) IF EOF(ThisFile) = FALSE THEN OUTPUT "Check terminated – too many errors" ELSE OUTPUT "There were ", ErrCount, " errors." ENDIF CLOSEFILE ThisFile ENDIF ENDFUNCTION
22. [1] (d) Incorrect block structure. Missing keyword denoting part of block (for example ENDPROCEDURE, ENDFUNCTION, ENDTYPE)
23. [1] (d) Data type errors, for example, assigning an integer value to a string
24. [1] (d) Identifier used before it is declared
25. [1] (d) Incorrect parameter use