1 Program Development l Problem definition l Problem analysis l Algorithm design l Program coding l Program testing l Program documentation

Problem Definition

3 ?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

5 ?The computer accepts a date of the year 1994 and outputs the date n days after the input date. How to solve the problem?

6 Problem Analysis - Input ?The computer accepts a date of the year 1994 and outputs the date n days after the input date. â A starting Date â The number of days that follows First, identify the input.

7 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?

8 Problem Analysis - Output ?The computer accepts a date of the year 1994 and outputs the date n days after the input date. Very Good! â The date n days after the input date

9 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?

10 Problem Analysis ?The computer accepts a date of the year 1994 and outputs the date n days after the input date. II  e got a solution!

Algorithm Design Top-down Modular Approach

12 Top-down Modular Design This is our initial problem Look_Up_Date

13 Structure Chart - Level 1 Look_Up_Date Break the problem down into subproblems Initialization Get_Input Calculate_Date Output_Date

14 Structure Chart - Level 2 Look_Up_Date Calculate_DateGet_InputInitializationOutput_Date Input Starting Input Number. Date of days Further break down if necesary

15 Structure Chart Completed Done! Look_Up_Date Input Starting Date Calculate_DateGet_InputInitialization Input Number of Days Output_Date

Program Coding Pseudocode

17 Pseudocode 1. Initialization 2. Get_Input 3. Calculate_Date 4. Output_Date

18 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 Language Pascal

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

23 Test Cases l Choose suitable test cases l Beware of Boundary Conditions l For Example, to test a program which decides whether an input number is greater than or equal to 100. l Three test cases should be used. l Do you know which three ?

24 Test cases (Continue...) l (1)any numbers small than 100 e.g. 50 l (2)the number 100 l (3) any numbers greater than 100 e.g. 200

Program Documentation

26 The End l Prepared by l Mr. Chan Hing Man ( )