Stages of program development process
The various stages in the development of a computer program are :
- Problem Definition
- Program Design
- The first step in the process of program development is the thorough understanding and identification of the problem for which is the program or software is to be developed.
- In this step the problem has to be defined formally.
- All the factors like Input/output, processing requirement, memory requirements, error handling, interfacing with other programs have to be taken into consideration in this stage.
- The next stage is the program design. The software developer makes use of tools like algorithms and flowcharts to develop the design of the program.
- Once the design process is complete, the actual computer program is written, i.e. the instructions are written in a computer language.
- Coding is generally a very small part of the entire program development process and also a less time consuming activity in reality.
- In this process all the syntax errors i.e. errors related to spelling, missing commas, undefined labels etc. are eliminated.
- For effective coding some of the guide lines which are applied are :
- Use of meaningful names and labels of variables,
- Simple and clear expressions,
- Modularity with emphasis on making modules generalized,
- Making use of comments and indenting the code properly,
- Avoiding jumps in the program to transfer control.
- At this stage the errors in the programs are detected and corrected.
- This stage of program development is an important process. Debugging is also known as program validation.
- Some common errors which might occur in the programs include:
- Un initialization of variables.
- Reversing of order of operands.
- Confusion of numbers and characters.
- Inverting of conditions eg jumping on zero instead of on not zero.
- The program is tested on a number of suitable test cases.
- A test plan of the program has to be done at the stage of the program design itself.
- This ensures a thorough understanding of the specifications.
- The most trivial and the most special cases should be identified and tested.
- It is always useful to include the maximum and minimum values of all variables as test data.
- Documentation is a very essential step in the program development.
- Documentation help the users and the people who maintain the software.
- This ensures that future modification if required can be done easily. Also it is required during redesigning and maintenance.
- Updating and correction of the program for changed conditions and field experience is accounted for in maintenance.
- Maintenance becomes essential in following situations:
- Change in specification,
- Change in equipment,
- Errors which are found during the actual execution of the program.