CLASS: SS2 WEEK:FOUR LESSON TOPIC: PROGRAM DEVELOPMENT II

CONTENT NOTE: PLS TAKE NOTE THAT SPACES SHOULD BE LEFT THE SAME WAY IT IS HERE Program development can be divided into several stages which are shown in the diagram below 1. Problem definition: This stage is the formal definition of task. It includes the specification of inputs and outputs processing requirements, system constraints( execution time, accuracy, response time), and error handling method 2. Problem Analysis: This step is the process of becoming familiar with the problem that will be solved with a computer program. The process ends when all the programmers’ questions have been resolved and requirement of the program are understood. 3. Flowcharting: ones the overall problem has been identified, the next stage of software development is program design. The programmer must decide, prior to writing his program, exactly which steps should the computer takes to solve an identified problem. This should be envisioned as a step by step procedure. The resulted diagram is called a flowchart 4. Desk Checking: Another way of testing the logic of a program is to carry out desk- check that is executing the statements of algorithm yourself on a sample data. 5. Program coding: The next step is the process of transforming the program logic design into a computer language format. This stage translates the program design into computer instructions. 6. Program compilation: in general the compiler will go through a few steps: a) Lexical Analysis: making sure all the symbols in the source code are legal and turning them into tokens for the next step b) Syntactic analysis: analyse the tokens, ensuring they follow the rules of the language grammar c) Code generation: uses syntax to create some form of intermediate language, often times assembly language d) Code optimization 7. Program Testing and Debugging: This stage is the discovery and correction of programming errors. Few programs run correctly the first time, so debugging is an important and time consuming stage of software development. Testing stage is the validation of the program. Testing makes sure the program performs correctly the required task. 8. Program Documentation: this stage is the documentation of the program so that who use and maintain it can understand it, so that program can be extended to further applications. A compiler: A compiler is a computer program or sets of programs that translates text written in a high level language( source Language) into another computer language (the target language) source code source w/substitution Flow diagram of a compiler An Interpreter: An interpreter is a computer program that executes other programs. This is in contrast to a compiler which does not execute its input program. exter A flow diagram of an interpreter Examples of Interpreted Languages are BASIC, COBOL Compiled languages are C, ALGOL, Visual Foxpro etc.