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Program Development

Problem definition Problem analysis Algorithm design Program coding Program testing Program documentation

Problem Definition

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Problem Definition

?The computer accepts a date of the year 1994 and outputs the date n days after the input date.

Here is our problem.

Problem Analysis

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Problem Analysis

?The computer accepts a date of the year 1994 and outputs the date n days after the input date.

How to solve the problem?

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Problem Analysis - Input

?The computer accepts a date of the year 1994 and outputs the date n days after the input date.

A starting Date The number of days that f

ollows

First, identify the input.

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Problem Analysis

?The computer accepts a date of the year 1994 and outputs the date n days after the input date.

The output is next, right?

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Problem Analysis - Output

?The computer accepts a date of the year 1994 and outputs the date n days after the input date.

Very Good!

The date n days after the input date

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Problem Analysis

?The computer accepts a date of the year 1994 and outputs the date n days after the input date.

What about the algorithm?

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Problem Analysis

?The computer accepts a date of the year 1994 and outputs the date n days after the input date.

IIe got a solution!

Algorithm Design

Top-down Modular Approach

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Top-down Modular Design

This is our initial problem

Look_Up_Date

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Structure Chart - Level 1

Look_Up_Date

Break the problem down into subproblems

Initialization Get_Input Calculate_Date Output_Date

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Structure Chart - Level 2

Look_Up_Date

Calculate_DateGet_Input Initialization Output_Date

Input Starting Input Number . Date of days

Further break down if necesary

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Structure Chart Completed

Done!

Look_Up_Date

Input Starting Date

Calculate_DateGet_Input Initialization

Input Number of Days

Output_Date

Program Coding

Pseudocode

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Pseudocode

1. Initialization

2. Get_Input

3. Calculate_Date

4. Output_Date

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Step-wise Refinement

2.1 Input Starting Date

2.2. Input Number of Days

1. Initialization 2. Get_Input

3. Calculate_Date 4. Output_Date

Program Coding

Programming LanguagePascal

program Look_Up_Date;

{ variable declarations }

:

{ procedure declarations }

:

:

begin

Initialization;

Get_Input;

Calculate_Date;

Output_Date

end.

program Look_Up_Date;

{ variable declarations }

var Year, Month, Day : integer;

{ procedure declarations }

:

:

begin

Initialization;

Get_Input ( Year, Month, Day );

Calculate_Date ( Year, Month, Day );

Output_Date ( Year, Month, Day )

end.

Program Tesing & Debugging

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Test Cases

Choose suitable test cases Beware of Boundary Conditions For Example, to test a program which decides

whether an input number is greater than or equal to 100.

Three test cases should be used. Do you know which three ?

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Test cases (Continue...)

(1) any numbers small than 100 e.g. 50 (2) the number 100 (3) any numbers greater than 100 e.g. 200

Program Documentation

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The End

Prepared by Mr. Chan Hing Man (96

044060)