Software Development Method (1.4 and 1.5)

Main steps:

1. Specify the Problem Requirements

· Get a statement of the problem

· Understand what is being asked for

Example:

A customer comes with the requirement for a program that converts number of miles to number of kilometers. The customer explains that users will input number of miles form the keyboard and that they expect to be shown the result on the computer screen in a neat format.

2. Analyze the Problem

· List the problem inputs

· List the problem outputs

· List other variables you may need to keep track of

· List any formulas that may be relevant

· Decide on the names and types of variables

· Decide how instructions and results are displayed

Example:

Problem Inputs: kilometers (distance in kilometers)

Problem Outputs: miles (distance in miles)

Additional Variables: none

Formulas: 1 mile = 1.609 kilometers

3. Design the Algorithm to Solve the Problem

· Develop a list of steps (called an algorithm) to solve the problem. Make sure (on paper) that the algorithm is correct. This step requires problem-solving skills!

· Don't attempt to solve every detail at once. Use top-down design (it is also called divide and conquer). This process is similar to writing a term-paper (p.23):

· List major steps of the algorithm (define subproblems)

· Solve subproblems (algorithm refinement)

· Common structure of every algorithm:

o Get the data

o Perform computations

o Display results

Example:

Outline of the conversion algorithm:

1. Get the distance in miles

2. Convert the distance to kilometers

3. Display the distance in miles

Refinement of step 2:

2.1. kilometers = 1.609 * miles

4. Implementation

Write (or code) each step of the algorithm in C programming language.

Example: Figure 1.14

5. Test and Verify the Completed Program

Compile and debug the program

Check if program works correctly:

· Validate the program output for several representative test cases that you calculate by hand

· Do not rely on a single test case – run the program several times using different inputs

· Check how robust the program is (how easy is to break it)

Document the testing procedure in the program header. It will tell people how hard you tried to make sure your code is foolproof

6. Maintain and Update the program

Often, there is a need to modify the program to meet changed requirements

In this phase, it becomes apparent why it is important to keep the code neat and well documented

Failure is the Natural Part of the Process!!

The first attempt at the solution is rarely completely correct

Do not be discouraged by initial failures