Fault-Error-Failure in a program The following procedure extract aims at counting the number of sheets in a book. At first, it computes the number of the last right page.

procedure Count_Number_of_Sheets (Sheets_Number:

Last_Right_Page: positive;

begin Last_Right_Page := ... ;

out positive) is Sheets_Number := (Last_Right_Page + 1) / 2;

end Count_Number_of_Sheets;

We assume that the expression which calculates the Last_Right_Page

(noted ... in the program) contains a fault. We use this procedure in a book editing processor to analyze a book whose actual last right page number is 325.

1. Is there a failure if the faulty expression gives 326 as a result? Answer the same question with 327 and 328.

2. Is there an error in the three cases?

3. What do you conclude from this experiment?