1. Program Development Life Cycle (PDLC)

2. Introduction
When programmers build software applications, they just do not sit down and start writing code. Instead, they follow an organized plan, or methodology, that breaks the process into a series of tasks.
There are many application development methodologies just as there are many programming languages. These different methodologies, however, tend to be variations of what is called the program develop.
The program development life cycle (PDLC) is an outline of each of the steps used to build software applications. Similarly to the way the System development lie cycle (SDLC) guides the systems analyst through development of an information system, the PDLC is a tool used to guide computer programmers through the development of an application.
The PDLC consists of six steps.

3. PDLC

4. Step 1: Analyze the Problem
Analysis includes
Decide what real word problem is. i.e. investigating the problem.
To solve and find how a program can do this.
The decisions of what the program should do.

5. Step 2: Design the Program
After analysis the best or optimum solution is chosen by the development team.
Large problem is broken up into smaller ones, & steps of the program are decided.
A tool that is available to help the programmer during this step is a Algorithm & Flowcharts.

6. Step 3: Code the Program
This step involves actually using an specific programming language to write lines of 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.
Some programs use interpreters that execute the lines of code one by one.
Other programming languages use 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.

7. Step 4: Test/Debug the Program
To make sure that the algorithm of your program does what it should, we need to test it.
An error in a 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.
While testing each module can be tested separately. When programmer has tested & verified each sub-module separately, the complete program must be tested to the satisfaction of the end user.

8. Step 5: Run/Execute the Program
When you run a C/C++ program, first the program will be compiled. This translates the source code into binary language.
After the program’s translator runs, the linker runs. The linker portion of the software connects your program with lines of code that are pre-written.
Larger numbers of files of this code are available in libraries. Libraries that can be linked to your code & take a lot of work away from you as a programmer.
When you run the program, you will do the 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 semi colon or added one where you shouldn’t have or misspelled a reserve word, these are all syntax errors. These are the easiest one to find because the program itself helps you to find them.

9. Step 5: Run/Execute the Program
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.
An example would be meaning/logic to add two numbers together and to then multiply the results, but writing the formula without the required parentheses. (2+3) * 5
Another type of error which is common is run time error. An example of run time error would be a program that tries to divide some number by zero. Dividing by zero is a illegal operation
One type of run time error is called linking error. If, in your computer program, you referred to use some code in a library and that library was not on your computer for some reason, you would get a run time message stating that the program could not run.

10. Step 6: Document & Maintain the Program
To 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.
Since many programmers work on teams, it is very important to have good internal documentation so that each programmer on the team can understand each other’s work.
It is also a fact that a programmer might start working on a program and then leave the company for whatever reason (or be placed onto another more urgent project).

11. Step 6: Document & Maintain the Program
The person who takes over that job needs to see the internal documentation so that he/she can pick up where the leaving programmer left off.
If you are a programmer who needs to update a program or correct a program you’ll not be very happy if the program is not documented. If you are in doubt, it is always better to have too much internal documentation than too little.
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.
To maintain is to make sure that the program keeps running as it should and to do any needed updating or fixing. Maintenance is the longest phase of the PFLC.

12. Step 6: Document & Maintain the Program
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.