Program Development Process

While writing a computer program, it is absolutely necessary to write .each and every instruction in the correct sequence. The logical control of element within the computer program is the most important aspect of programming.

The various stages in the development of a computer program are :

· Problem Definition

· Program Design

· Coding

· Debugging

· Testing

· Documentation

· Maintenance

Problem Definition:

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.

Program Design:

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.

Algorithm:

An algorithm represents the logic of the processing to be performed. It is a sequence of instructions which are designed in such a way that if they are executed in the specified sequence, the desired goal is achieved. It is imperative that the result be obtained after execution of a finite number of steps.

In an algorithm,

- Each and every instruction has to be precise and clear.

- The instruction has to be executed in a finite time.

- When the algorithm terminates the desired result should be achieved.

 Flowchart:

A flowchart is a pictorial representation of the algorithm. It represents the steps involved in the procedure and shows the logical sequence of processing using boxes of different shapes. The instruction to be executed is mentioned in the boxes. These boxes are connected together by solid lines with arrows, which indicate the flow of operation.

The first step in the design of a program is the algorithm. The algorithm is then represented in the form of a flowchart and the flowchart is then expressed in the computer language to actually prepare the computer program.

The symbols used in the flowchart are:

Terminal (Start/Stop): The symbol denotes the beginning, ending and halt operation in the program logic. Thus it is the first and the last Symbols! in any nov-chart to indicate the start and stop of the process.

Input/output: Indicates when an input or output operation is to performed in the process.

Processing: This represents the arithmetic operations like addition, subtraction etc, and the movement of data in the process

Decision: The decision symbol is used to represent a point where one or more alternatives is possible. The criteria for decision making are written in the decision box. On each path the condition for which the particular path is to be followed has to be written. During the execution the appropriate path will be followed depending upon the result of the decision.

Flow lines: These indicate the flow of operation ie. The sequence of instruction execution. Flow lines are normally drawn with arrowhead indicating the direction of flow of the program.

Connectors: A connector is used to indicate the logic flow from one page to another when the flowchart becomes very long. Connectors do not represent any operation. They are mainly used in the flowchart for clarity and convenience.