Fourth Generation Languages (4 GL)

Programming languages are sometimes classified with generations - from the lowest to the highest.

The First Generation - Machine Language

The Second Generation - Assembly Language

The Third Generation - High4.evel Language

Unlike procedural languages which require that a programmer writes all the steps to complete the program and generate output, which are related to a more structural approach towards programming. It is the first standardized language.

· BASIC:

BASIC stands for Beginners All Purpose Symbolic Instruction Code. The language was developed by Prof. John Kemeny and Thomas Kurtz in USA. It irrelatively easy to learn. Programs written in BASIC language are interpreted. It resembles FORTRAN in many ways, but can also be effectively used in business applications. Thus it can be used for both business and scientific applications. BASIC is one of one most popular language for use in microcomputer systems.

· COBOL:

Common Business Oriented Language was designed especially for business applications. A COBOL program is constructed from sentences, paragraphs, sections and divisions. A COBOL program must have four divisions: the identification division, the environment division, data division, and the procedure division. Thus COBOL is a self documenting language. It is one of the most widely used commercial languages.

· RPG:

Report Generator is a general purpose, business oriented language designed to generate output reports. The language was developed by IBM and was launched for use on the IBM 1401 computer. It is best suited for applications where large data files have to be read and extensive reports are to be output. It has limited mathematical capability and is not suited for scientific applications.

· PASCAL:

PASCAL has been named after the French mathematician Blaise Pascal; It allows the programmer to structure the programming language. The features of PASCAL allow it to be used for both scientific and business applications. It is a very powerful language. It is implemented on several computers including microcomputers and minicomputers and is also widely used to teach programming to students and beginners.

· C:

C was designed and developed at Bell Laboratories USA. It is a block structured language which allows the use of various concepts of structured programming. C also has the advantage of being able to manipulate internal processor registers of the computer. Thus it has some powers of the assembly language. C is also very portable. C is the most popular language used for systems programming like designing compilers and operating systems.

· LISP:

LISP stands for list processing. This language is mostly used in non numeric applications which require logical rather than numerical operations. Therefore it is widely used in games, pattern recognition and artificial intelligence.