An Overview of Programming

An Overview of Programming : Although computers can perform complex and difficult operations, they need to be told exactly what to do and they must be instructed in a precise and limited language that they can Programming in C 7 understand. These instructions are known as software. The machinery that actually executes the instructions is known as hardware. At the hardware level, computers understand only simple commands such as “copy this number”, “add these three numbers”, “compare these two numbers” etc. Such commands constitute the computer’s instruction set and programs written in the computer’s machine language. It is extremely tiresome to write programs in machine language because even the simplest tasks require many instructions. Moreover, in most machine languages, everything such as instructions, data, variables etc, are represented by binary numbers. Binary numbers are composed of zeros and ones, each digit is called a bit which is the short form of binary digit. These programs, consisting of a jumble of zeros and ones are difficult to write, read and maintain. In early stages (1940s & 1950s), all programs were written in machine language or its improved version, known as assembly language. In assembly language, each instruction is identified by a short name rather than a number and variables can be identified by names rather than numbers. Programs written in assembly language require a special program, called an assembler, to translate assembly language instructions into machine instructions. These days, programs are written in assembly language only when execution speed is a high priority. Presently, majority of programs are written in languages called high-level languages which were first developed in the 1950s and 1960s. High-level languages allow programmers to write programs in language more natural to them than the computer’s restrictive language. Broadly speaking, programming languages can be viewed as lying along a spectrum with machine languages at one end and human languages, such as English, French, Russian etc, at the other end. High-level languages fall somewhere in between these extremes, usually closer to the machine language. High-level languages allow programmers to deal with complex objects without worrying about details of the particular computer on which the program is running. Of course, programming languages differ from human languages since they are designed specially to manipulate informations. They are much more limited and precise than human languages.