Computer Science 255


Third Hour Exam




Name ______________________

















Monday, Nov. 26
100 pts.


1.	(15 pts.)	List and briefly describe the three main file 
organizations, paying particular attention to the ways in which 
records may be accessed.


2.	(15 pts.)	List and briefly describe the five steps in the life-
cycle model for software development.

3.	(30 pts.)	Records in the file MASTER.DAT have the following 
organization:

	01	MASTER-REC.
		02	PNO			PIC X(5).
		02	PNAME 		PIC X(20)
		02	AMT-ON-HAND	PIC 999.

	The file TRANS.DAT contains variable length records for 
insertion and deletion only (with only one transaction / part 
number).  Each record contains a part number (PNO) followed 
by a transaction code (PIC X) containing a "D" for deletion 
transactions and an "I" for insert transactions.

a.	(10 pts.)	Write the variable length file (FD) description for 
this file.

b.	(20 pts.)	Write the PROCEDURE DIVISION entries (only) to read 
MASTER.DAT and TRANS.DAT and create a new master file, processing 
insertions and deletions in TRANS.DAT.  Check for out of sequence 
conditions, for the attempted insertion of an existing record, and for the 
attempted deletion of a non-existent record.  Assume reasonable 
variable names (i.e., you do not need to write the DATA DIVISION entries, 
and announce errors with a suitable DISPLAY statement (i.e., you do not 
need an error listing file).


4.	(10 pts.)	Assume the following sequence of keys in a file.  

File A:	10 / 30 / 20 / 50 / 60 / 5 / 25 / 35 / 15 / 40 

a.	What is the arrangement of keys in files B and C in a 
distribution-merge sort?

File B:


File C:


b.	What is the arrangement of keys after a merge back into file A 
in a distribution merge-sort?

File A:


5.	(10 pts.)  What is the impedance mismatch problem with the 
COBOL SORT verb, and how does COBOL get around it?


6.	(20 pts.)	The table PNO-TABLE contains 30 part records as 
follows:

		02	PNO			PIC X(5).
		02	PNAME 		PIC X(20)
		02	AMT-ON-HAND	PIC 999.

	The table is sorted in ascending order by part number.

a.	(5 pts.)	Write the COBOL description for this table, setting it 
up for a binary search (note that this is a repeat of a question 
in the last exam).










b.	(15 pts.)	Write the COBOL SEARCH verb which will look for 
the part record with PNO = "12345", DISPLAYing a message if 
the part is not found, and the name of the part if it is found.



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