Software Engineering | Program Development Life Cycle (PDLC)



Program Development Life Cycle (PDLC) is a systematic way of developing quality software. It provides an organized plan for breaking down the task of program development into manageable chunks, each of which must be successfully completed before moving on to the next phase.

The program development process is divided into the steps discussed below:

  1. Defining the Problem –
    The first step is to define the problem. In major software projects, this is a job for system analyst, who provides the results of their work to programmers in the form of a program specification. The program specification defines the data used in program, the processing that should take place while finding a solution, the format of the output and the user interface.



  2. Designing the Program –
    Program design starts by focusing on the main goal that the program is trying to achieve and then breaking the program into manageable components, each of which contributes to this goal. This approach of program design is called top-bottom program design or modular programming. The first step involve identifying main routine, which is the one of program’s major activity. From that point, programmers try to divide the various components of the main routine into smaller parts called modules. For each module, programmer draws a conceptual plan using an appropriate program design tool to visualize how the module will do its assign job.

    Program Design Tools:
    The various program design tools are described below:

    • Structure Charts – A structure chart, also called Hierarchy chart, show top-down design of program. Each box in the structure chart indicates a task that program must accomplish. The Top module, called the Main module or Control module. For example:

    • Algorithms –
      An algorithm is a step-by-step description of how to arrive at a solution in the most easiest way. Algorithms are not restricted to computer world only. In fact, we use them in everyday life.
    • Flowcharts –
      A flowchart is a diagram that shows the logic of the program. For example:

    • Decision tables –
      A Decision table is a special kind of table, which is divided into four parts by a pair of horizontal and vertical lines.
    • Pseudocode –
      A pseudocode is another tool to describe the way to arrive at a solution. They are different from algorithm by the fact that they are expressed in program language like constructs.
  3. Coding the Program –
    Coding the program means translating an algorithm into specific programming language. The technique of programming using only well defined control structures is known as Structured programming. Programmer must follow the language rules, violation of any rule causes error. These errors must be eliminated before going to the next step.

  4. Testing and Debugging the Program –
    After removal of syntax errors, the program will execute. However, the output of the program may not be correct. This is because of logical error in the program. A logical error is a mistake that the programmer made while designing the solution to a problem. So the programmer must find and correct logical errors by carefully examining the program output using Test data. Syntax error and Logical error are collectively known as Bugs. The process of identifying errors and eliminating them is known as Debugging.

  5. Documenting the Program –
    After testing, the software project is almost complete. The structure charts, pseudocodes, flowcharts and decision tables developed during the design phase become documentation for others who are associated with the software project. This phase ends by writing a manual that provides an overview of the program’s functionality, tutorials for the beginner, in-depth explanations of major program features, reference documentation of all program commands and a thorough description of the error messages generated by the program.

  6. Deploying and Maintaining the Program –
    In the final phase, the program is deployed (installed) at the user’s site. Here also, the program is kept under watch till the user gives a green signal to it.
    Even after the software is completed, it needs to be maintained and evaluated regularly. In software maintenance, the programming team fixes program errors and updates the software.


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