Languages are a means of communication. Normally people interact with each other through a language. On the same pattern, communication with computers is carried out through a language. This language is understood both by user and the machine.
Just as every language like English, Hindi has its grammatical rules; every computer language is bound by rules known as SYNTAX of that language. The user is bound by that syntax while communicating with the computer system.
Computer languages are broadly classified as:
The term low level means closeness to the way in which machine understand. The low level languages are:
Machine Language: This is the language (in the form of 0’s and 1’s, called binary numbers) understood directly by the computer. It is machine dependent. It is difficult to learn and even more difficult to write programs.
Assembly Language: This is the language where the machine codes comprising of 0’s and 1’s are substituted by symbolic codes (called mnemonics) to improve their understanding. It is the first step to improve programming structure.
Assembly language programming is simpler and less time consuming than machine level programming, it is easier to locate and correct errors in assembly language than in machine language programs. It is also machine dependent. Programmers must have knowledge of the machine on which the program will run.
Low level language requires extensive knowledge of the hardware since it is machine dependent. To overcome the limitation, high level language has been evolved which uses normal English like, easy to understand statements to solve any problem. Higher level languages are computer independent and programming becomes quite easy and simple.
Various high level languages are:
BASIC (Beginners All Purpose Symbolic Instruction Code): It is widely used, easy to learn general purpose language. Mainly used in microcomputers in earlier days.
COBOL (Common Business Oriented language): A standardized language used for commercial applications.
FORTRAN (Formula Translation): Developed for solving mathematical and scientific problems. One of the most popular languages among scientific community.
C: Structured Programming Language used for all purpose such as scientific application, commercial application, developing games, etc.
C++: Popular object oriented programming language, used for general purpose.
High Level language is machine independent and assembly language though it is machine dependent yet mnemonics that are being used to represent instructions are not directly understandable by machine. Hence, to make the machine understand the instructions provided by both the languages, Compiler and Assembler are required to convert these instructions into machine language.
The software (set of programs) that reads a program written in high level language and translates it into an equivalent program in machine language is called as Compiler. The program written by the programmer in high level language is called source program and the program generated by the compiler after translation is called as object program.
The software (set of programs) that reads a program written in assembly language and translates it into an equivalent program in machine language is called as Assembler.