1. JACKSON Structured Programming

2. It was developed by Michael Jackson – it is a systematic technique for mapping the structure of a problem into program structure

3. The mapping is accomplished in 3 steps
Specifying input and output data structures using tree structured diagrams
Identify the correspondence between nodes in the output and input trees
The structural model of the program is expanded into a detailed design model that contains the operations needed to solve the problem

4. Input and output structure are specified using a graphical notation to specify
data hierarchy
Sequences of data
Repetition of data items
alternate data items

5. First Step : Tree StructureA B C D E F G H I

6. Second Step
Identify the points of commonality in the input and output structure and combining the two structures into a program structure

7. Third Step It has 3 sub steps
1) A list of operations required to perform the processing steps is developed
2) The operations are associated with the program structure
3) Program structure and operations are expressed in a notation called schematic logic, which is stylized pseudo code. Control flow for selection and iteration are specified in this step.

8. Example
Input file – collection of inventory records sorted by part number
Part number – each record contains it (field). It’s the number of units of that item issued or received in one transaction
Output record - contains heading and Net movement line for each part number in the input file
Because the input file is sorted by part number, all issues and receipts of a given part number are in a contiguous portion of the file called a part group.
Each record in the part group is called a movement record.

9. Step 1: Tree Structure (i/o struct)
Input file
Output Record
Part Group
Heading
Body
Movement
Record
Net Movement Line
Issue
Receipt

10. Step 2: Correspondence Input file Output Record Part Group Heading
Body
Movement
Record
Net Movement Line
Issue
Receipt

11. After corresponding the resultant structure will be as follows: It’s a program structure for an inventory problem
program
Process
heading
Process Body
Process
PTGP and Line
Process
PTGP body
Process
Line
Process Record
Process issue
Process
Receipt

12. Step3 : Sub Step1 List of Operations needed in the inventory program
Open Files
Close Files
Stop Run
Read a record into PART_NUM,MOVMNT
Write Heading
Write NET_MOVEMENT Line
Set Net_Movmnt to zero
Add MovMnt to Net_Movmnt
Subtract movmnt from net_movment

13. Sub Step 2 (Association of Operations)
program
Process
heading
Process Body 2 3 1 4 5
Process
PTGP and Line
Process
PTGP body
Process
Line 7 6
Process Record 4 9
Process issue
Process
Receipt 8

14. Sub Step 3 (Schematic Logic Representation)
BEGIN PROGRAM
OPEN FILES
READ PART_NUM, MOVMNT
WRITE HEADING
ITERATE WHILE NOT(END-OF-FILE)
SET NET-MOVMNT TO ZERO
ITERATE WHILE SAME-PART-NUM
IF (MOVMNT= ISSUE) THEN
SUB MOVMNT FROM NET-MOVMNT
ELSE IF (MOVMNT = RECEIPT) THEN
ADD MOVMNT TO NET-MOVMNT
END IF
READ PART-NUM,MOVMNT
END WHILE
WRITE NET-MOVEMENT LINE
CLOSE FILES
STOP
END PROGRAM