Program Development Life Cycle

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In today’s Computer Science class, We will be learning about Program Development Lifecycle. We hope you enjoy the class!

The program development life cycle (PDLC) is an outline of each of the steps used to build software applications. Just like the system development life cycle (SDLC) guides the system analyst through the development of an information system, so also program development life cycle is a tool used to guide computer programmers through the development of an application.

Steps Involved in Program Development Cycle

1. Analyze the problem – Precisely define the problem to be solved, and write program specifications – descriptions of the program’s inputs, processing, outputs, and user interface.
2. Design the program – Develop a detailed logic plan using a tool such as pseudo-code, flowcharts, object structure diagrams, or event diagrams to group the program’s activities into modules; devise a method of solution or algorithm for each module and test the solution algorithms.
3. Code the program – Translate the design into an application using a programming language or application development tool by creating the user interface and writing code; include internal documentation – comments and remarks within the code that explain the purpose of code statements.
4. Test and debug the program – Test the program, finding and correcting errors (debugging) until it is error-free and contains enough safeguards to ensure the desired results.
5. Formalize the solution – Review and, if necessary, revise internal documentation; formalise and complete end-user (external) documentation.
6. Maintain the program – Provide education and support to end-users; correct any unanticipated errors that emerge and identify user-requested modifications (enhancements). Once errors or enhancements are identified, the program development life cycle begins again at Step 1.

Step 1: Define (Analyze the Problem)

Decide what problem is to be solved and how a program can do this. The decisions of what the program should do. Look at the data flow, the form of the input and output, the process needed and the interaction. A defining diagram helps the programmer to see the components.

Step 2: Outline (Design the Program)

Breaking a large problem up into smaller ones. Deciding what the steps of the program are. A tool that is available to help the programmer during this step is a Flowchart, which is a visual diagram of the flow of the program.

Step 3: Develop an Algorithm

An algorithm is the step that a programmer will write that will become a program. It is written in the form of structured language called Pseudo-code. Pseudo-code is language non-specific; it could be used by any programmer to help him or her write the actual program using any programming language. Each step of your algorithm will be directly translated into a line of code when it is time to write the program using the programming language. One line of the algorithm is equal to one line of code. After creating the flowchart, you will write the algorithm using pseudo-code. Pseudo-code should not use any reserved word. A reserved word, also known as a keyword, is a word that is reserved or used by any specific programming language to accomplish something.

An algorithm must be:

1. Be lucid, precise, and unambiguous
2. Give the correct solution in all cases
3. Eventually end (be complete)

Step 4: Code (Code the Program)

The use of specific programming language to write lines of the program. These lines of code are also called the listing and are also known as the source code. The program that you run is called the object code. When you use Word, you are using the object code. The actual lines of instruction, written by the programmer, that make Word run are the source code. Some programs execute the lines of code one by one; these types of programming languages are known as interpreters. The advantage of an interpreter is that, for a programming student, they are much easier to learn, as you can write one line of code and immediately test it to make sure works. The disadvantage is that these programs run slower. Basic and HTML are interpreters. Other programming languages are compilers; they execute the entire program at one time. These programs execute much faster but require a programmer to write an entire program to test a section. C++ is a compiler.

Step 5: Test (Debugging the Program)

To ensure that the algorithm of your program does what it should, you need to test the program. An error found in the program is known as a bug and the process of finding bugs is known as debugging. Desk checking is looking at lines of code one by one to see if they have been written correctly and the logic is correct. Desk checking is also called tracing. The walkthrough is just when a group of people do a desk check.

Step 6: Run and Execute 

This means the process of running the program on a computer. When you run a C++ program, first the program will compile the program. This translates the human code into binary language. When you run the program, you will do further testing. There are two main types of errors, syntax and logic errors.

Syntax errors are problems with grammar, spelling, or punctuation. If you have left of a semicolon or added one where you shouldn’t have or misspelt a reserved word, these are all syntax errors. These are the easiest ones to find because the program itself helps you to find them.

Logic errors are errors that make a program’s results incorrect. These are much more difficult to find. No compiler will stop and tell you that you have a logic error.  To the computer, which is a stupid thing that only follows orders, there is nothing incorrect about a logic error. You, the programmer, need to find the logic errors by yourself.

Step 7: Documentation

The document is to put together all of the materials that have been generated throughout the PDLC process. All of the flowcharts, messages, algorithms, lines of code, and the user manuals are part of this documentation.

Internal documentation is used by other programmers to help them know why you did something a certain way or tell them how you wrote a program.

External documentation includes user manuals and anything that is not the actual code or is part of the listing. This should also include materials that are placed on a website such as FAQs (frequently asked questions) and help areas.

Step 8: Maintenance

The process of maintenance is to make sure that the program keeps running as it should and also this includes updating or fixing. Maintenance is the longest phase of the PDLC. As users use the program, they will notice things that need to be fixed or updated. No matter how many times you test a program to make sure that it will work as expected, it is only when it actually gets into the hands of the actual end-user that some of these errors show up. You will continue to fix and update the program until it reaches a point where the program has become redundant or too old. At that time, maintenance stops and the PDLC is started all over again.

 

We have come to the end of this class. We do hope you enjoyed the class?

Should you have any further question, feel free to ask in the comment section below and trust us to respond as soon as possible.

In our next class, we will continue learning about Algorithms. We are very much eager to meet you there.

 

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