2014 Old Spec

Question 4

Create a folder/directory Question4 for your new program. The algorithm, represented using pseudo-code in Figure 5, and the variable table, Table 3, describe the process of using a check digit to check if a value entered by the user is a valid 13 digit International Standard Book Number (ISBN).

Figure 5

   FOR Count 1 TO 13 DO 

       OUTPUT "Please enter next digit of ISBN: "

       INPUT ISBN[Count]

   ENDFOR

   CalculatedDigit = 0

   Count = 1

   WHILE Count < 13 DO

       CalculatedDigit = CalculatedDigit + ISBN[Count]

       Count = Count + 1

       CalculatedDigit = CalculatedDigit + ISBN[Count] * 3

       Count = Count + 1

   ENDWHILE

   WHILE CalculatedDigit >= 10 DO

       CalculatedDigit = CalculatedDigit – 10

   ENDWHILE

   CalculatedDigit = 10 – CalculatedDigit

   IF CalculatedDigit = 10

       THEN CalculatedDigit = 0

   ENDIF

   IF CalculatedDigit = ISBN[13]

       THEN OUTPUT "Valid ISBN"

       ELSE OUTPUT "Invalid ISBN"

   ENDIF

Table 3

Identifier	Data Type	Purpose
ISBN	Array[1..13] Of Integer	Stores the 13 digit ISBN entered by the user – one digit is stored in each element of the array.
Count	Integer	Used to select a specific digit in the ISBN.
CalculatedDigit	Integer	Used to store the digit calculated from the first 12 digits of the ISBN. It is also used to store the intermediate results of the calculation.

What you need to do

1. Write a program for the algorithm in Figure 5.
   
2. Test the program by showing the result of entering the digits 9, 7, 8, 0, 0, 9, 9, 4, 1, 0, 6, 7, 6 (in that order).
   
3. Test the program by showing the result of entering the digits 9, 7, 8, 1, 8, 5, 7, 0, 2, 8, 8, 9, 4 (in that order).
   
4. Save the program in your new Question4 folder/directory.