1. The Program Development Cycle

2. Program Development Cycle
Modern software developers base many of their techniques on traditional approaches to mathematical problem solving.
One such approach is based on the how engineers solve problems.

3. Program Development Cycle
Engineers must:
Design a solution to a problem
Implement the solution
Test the solution
Fix any errors in the solution

4. Program Development Cycle
This approach can be used in computer programming:
Design a solution to a problem (design a program)
implement the solution (code the program )
Test the solution (test the program)
Fix the solution (debug the program)

5. Program Development Cycle
Once the software is working, improvements can be designed into the system. This leads back to design, creating a four-phase cycle.

6. Program Development Cycle

7. Program Development Cycle
Many different techniques are used to design methods in new software. Top-down development and modular design are most common.
Tools include flowcharts, pseudo-code, storyboards, and Universal Modeling Language (UML).

8. Program Development Cycle
In the design phase of object-oriented programming, objects must be chosen from libraries, or the properties and methods for new objects must be described.

9. Program Development Cycle

10. Program Development Cycle
The program development cycle’s code phase includes translating a software design into a particular language, and then entering that language on the computer.

11. Program Development Cycle

12. Program Development Cycle
Testing can be rather complicated:
Does the new method do what it is supposed to do? This is known as a test for correctness. Tests for correctness measure whether the program meets the original specifications.

13. Program Development Cycle
Testing can be rather complicated:
Is the method reasonably efficient? How much time does it take for the method to complete its task, and how much space does it use?

14. Program Development Cycle
Testing can be rather complicated:
Does the method have any undesirable side effects? How does one program affects the performance of another program, or one method affects another method?

15. Program Development Cycle
Programmers perform unit tests and integration tests.
A unit test checks to see if a method works as expected all by itself.
An integration test checks to see if a method works in combination with other methods.

17. Program Development Cycle
Programmers perform unit tests and integration tests.
A unit test checks to see if a method works as expected all by itself.
An integration test checks to see if a method works in combination with other methods.

18. Program Development Cycle

19. Program Development Cycle
The causes of any problems discovered during testing need to be isolated. Here unit tests are most helpful.
Once you know the cause, you can develop a plan for fixing the problem, modify the necessary methods, and then test again.

20. Program Development Cycle

21. An Alice Development Cycle