What is Computer Programming?
A program is a set of instructions that guide the computer in carrying out a specific task. To write a program you need to have a programming language (software) such as: Visual Basic, Turing, Basic, Java, Fortran, Cobol, C++, etc. These are English-like languages that humans can read, understand and write, however the computer can not understand these languages!
In order for the computer to carry out the instructions, the program must be translated to a language the machine understands, called machine language and then executed. The programs we write in Visual Basic are first translated by the VB software. When the statements in the original or source program are translated to machine language, called the object program, the program is said to be compiled and ready for execution
Why Write Programs
All the software we use on the computer are programs written to carry out various applications. Even DOS and Windows is a program (or set of programs) written as an interface between the user and the hardware. DOS and Windows are operating systems. Without one of them we would need to know a great deal more to communicate with, and manage the hardware components of the computer system. Windows is a software package that allows us to work in DOS without needing to understand all the built in commands. It makes the computer friendlier to use because the menus and icons replace the need to remember all the DOS commands.
There is software referred to as application software such as; word processors (MS Works/Word), spreadsheets (Works,Lotus,Excel), desktop publishing (Pagemaker, Ventura Publisher) , database programs (Access,dBASE, Paradox,) graphics programs (CorelDRAW, AutoCAD) and communications software (PCtalk, HyperAccess). These programs are built to to particular types of jobs and allow us to process information easily.
If information needs to be processed in a repetitive manner then programming a computer to carry out the task will make the job quicker and easier.
Steps To Creating a Program:
Software refers to a collection of instructions, called a program ( VB calls them a solution) that directs the hardware (monitor, keyboard, mouse, CPU etc.)
The first step in writing instructions to carry out a task is to determine what the output should be. The second step is to identify the data, or input, necessary to obtain the output. The last step is to determine how to process the input to obtain the output. Therefore, the problem solving process used will always consist of three steps:
When solving a computer problem, each assignment asks you to first create an IPO chart. IPO stands for input, processing and output. IPO charts are done before you start to code. IPO charts state the processing in a structured english, sometimes called pseudo-code. For example:
Create an IPO chart for a program that will allow a person to input an amount to be deposited in a bank account, the interest rate and the number of years the money will be left in the account. Print the amount of money in the account at the end of the time.
Input Processing Output
amount deposited interest rate number of years final amount = amount deposited
repeat for the number of years
final amount = final amount + final amount * interest rate final amount
Notice that the IPO chart ‘explains’ how to change the input to the output. All the inputs are used in the processing and the outputs are clearly calculated in the processing. The processing is structured and indented similar to VB programs but the language is more like ‘normal’ English than a programming language. Many VB details are not included, such as dim, end if, next, to String, because they are ‘understood’ to be needed when you start to code.
System Development Life cycle
When working in teams of programmers, or on large programming projects, it is important to stay organized. Many efficient programmers plan their programs using the system development life cycle or SDLC. The step-by-step process is shown below:
Explanation How to..
Analysis Define and understand the problem Be sure you understand what the program should do, that is, what the input and output should be.
Design Plan the solution to the problem Find a logical sequence of precise steps that solve the problem.Create the IPO chart, in this class.
A sequence of steps such as this is called an Algorithm. Three popular methods used to develop logical plans are flowcharts, pseudo code and top-down charts. These tools or methods will assist the programmer in breaking down a large problem into smaller tasks.
Choose the Interface
Determine how the input will be obtained and how the output will be displayed – layout the form(s)
Development Code Create the form and translate the algorithm into a programming language. The program is written during this stage. Write comments inside the program that explain to other programmers what the code is doing.
Testing Test and Debug Locate and remove any errors in the program.
Implementation Install the working program on the user’s computer and train the user Write documentation that is intended to allow another person to understand the program and train the user how to use the program.