Jka: /* Sample COBOL Program */

2007-02-22T20:02:45Z

Sample COBOL Program

Jka at 20:01, 22 February 2007

2007-02-22T20:01:24Z

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==Program Development Process==
===Program Specifications===
* System analysts, users, and programmers develop specifications
* Specifications include:
** Description of input and output data
** Step-by-step processing required to convert input to output
Record layout forms describe format of input and output data
* Data names of each data item in record
* Location of each data item in record
* Size of each data item
* Number of decimal positions (for numerica data items)
===Design the program===
Program planning tools used to map out structure and logic of program
* Flowcharts use block diagrams to represent logic
* Pseudocode uses English-like statements
* Hierarchy charts show relationships among sections of program
====Improving Program Design====
Two techniques used to develop programs that are easier to understand, test, debug, and modify
* Structured Programming
* Top-Down programming
=====Structured Programming=====
Program divided into paragraphs
* Main paragraph or module control logic flow using PERFORM statements
* Main module "performs" other modules when instructions in that module are required
* Each module can be written and tested independently of others
=====Top-Down Programming=====
For COBOL program
* Code main modules or routines first
* Code intermediate modules next
* Details deferred to minor modules and coded last
===Code and Enter Program===
* Programmer writes and enters program into computer
* Program written in symbolic language (like COBOL)
* Called source program
===Compile Source Program===
Compiler is program that
* Checks source program for rule violations
* Translates source program into object program
===Test Program===
* Test or debug program to ensure it contains no errors
* Check for two types of errors
** Compile-time errors
** Execution errors
====Compile-Time Errors====
* Errors detected by compiler during translation from COBOL to machine language
* Detects violations of programming rules
** Misspelled reserved words
** Missing punctuation
* Also called [[syntax error]]s
====Execution Errors====
* Detected when program is run
* Logic error causes incorrect output
** Sequence of instructions incorrect
** Wrong instruction coded
* Run-time error if computer cannot execute instruction
** Attempt to divide by zero
** Attempt to read a file that cannot be found
====Debugging Techniques====
* Desk checking
* Correcting syntax errors
* Program walkthroughs
* Executing the program
===Document the Program===
* Documentation - formal set of procedures and instructions to specify how to use program
* Written for:
** Those working with output
** Computer operators who run program
** Maintenance programmers who make modifications to program
==Sample COBOL Program==
<pre>
IDENTIFICATION DIVISION.
PROGRAM-ID. WAGESBATCH.
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
SELECT EMPLOYEE-DATA ASSIGN TO “/home/seemab/EMP-DAT.in".
SELECT PAYROLL-LISTING ASSIGN TO “/home/seemab/EMP-OUT-DAT.out".

DATA DIVISION.
FILE SECTION.
FD EMPLOYEE-DATA.
01 EMPLOYEE-RECORD.
05 EMPLOYEE-NAME-IN PIC X(20).
05 HOURS-WORKED-IN PIC 9(2).
05 HOURLY-RATE-IN PIC 9V99.

FD PAYROLL-LISTING.
01 PRINT-REC.
05 PIC X(20).
05 NAME-OUT PIC X(20).
05 PIC X(10).
05 HOURS-OUT PIC 9(2).
05 PIC X(8).
05 RATE-OUT PIC 9.99.
05 PIC X(10).
05 WEEKLY-WAGES-OUT PIC 999.99.

WORKING-STORAGE SECTION.
01 ARE-THERE-MORE-RECORDS PIC XXX VALUE "YES".
PROCEDURE DIVISION.
100-MAIN.
OPEN INPUT EMPLOYEE-DATA
OUTPUT PAYROLL-LISTING

PERFORM UNTIL ARE-THERE-MORE-RECORDS = "NO"
READ EMPLOYEE-DATA
AT END
MOVE 'NO ' TO ARE-THERE-MORE-RECORDS
NOT AT END
PERFORM 200-WAGE-ROUTINE
END-READ
END-PERFORM
CLOSE EMPLOYEE-DATA
PAYROLL-LISTING
STOP RUN.

200-COMPUTE-WAGE-ROUTINE.
MOVE SPACES TO PRINT_REC
MOVE EMPLOYEE-NAME-IN TO NAME-OUT
MOVE HOURS-WORKED-IN TO HOURS-OUT
MOVE HOURLY-RATE-IN TO RATE-OUT
MULTIPLY HOURLY-RATE-IN BY HOURS-WORKED-IN GIVING WEEKLY-WAGES-OUT
WRITE PRINT-REC.
</pre>

← Older revision		Revision as of 20:02, 22 February 2007
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	WRITE PRINT-REC.		WRITE PRINT-REC.
	</pre>		</pre>
		+	==[[COP 2121 Basic Cobol Program Structure]]==

COP 2121 Program Development Process - Revision history

Jka: /* Sample COBOL Program */

Jka at 20:01, 22 February 2007