20. “Pascal programming language” Pascal programming language From Wikipedia, the free encyclopedia.

The computer programming language Pascal is one of the landmark programming languages on which generations of students cut their teeth and variants of which are still widely used today. TeX and much of the original Macintosh operating system were written in Pascal.

The Swiss computer scientist Niklaus Wirth developed Pascal in 1970, first as a hypothetical language that would encourage students to write structured code. Pascal is based on the Algol programming language and is named in honor of mathematician and philosopher Blaise Pascal. Wirth also developed Modula-2 and Oberon, languages similar to Pascal which also support object-oriented programming.

Overview

All Pascal programs start with the "Program" keyword, an optional list of internal filedescriptors and then a block of code is indicated with the "Begin" / "End" keywords. Letter case is ignored in the Pascal language. Semicolons separate statements, and the full stop ends the program (or unit). For some compilers the 'Program' line is optional.

Pascal, in its original form, is a purely procedural language with the standard array of if, while, for, and related constructs.

Turbo Pascal, and other derivatives with units or module concepts are modular languages. Turbo Pascal copied these concepts from either a draft of the Extended Pascal standard or Pascal's successor Modula-2, however doesn't provide a nested module concept.

Hello World

program HelloWorld(input,output);

begin

Writeln('Hello, World!');

end.

Notes: It is not nessesary to add 'input,output'

Major languages

The following are major programming languages used by at least several thousand programmers worldwide:

Ada , ALGOL , APL , AWK , BASIC , C , C++ , C# , COBOL , ColdFusion , Common Lisp , Delphi , Eiffel , Focus , Fortran , Haskell , IDL , Java , JavaScript , Lisp , Objective-C , OCaml , Pascal , Perl , PHP , Prolog , Python , Ruby , SAS , Scheme , Smalltalk , SQL , Visual Basic. COBOL is a second-generation programming language. Its name is an acronym, for COmmon Business Oriented Language, defining its primary domain in business, finance, and administrative systems for companies and governments.

Prehistory and specification

COBOL was initially created in 1959 by The Short Range Committee, one of three committees proposed at a meeting held at the Pentagon in May 1959, organized by Charles Phillips of the United States Department of Defense. The Short Range Committee was formed to recommend a short range approach to a common business language. It was made up of members representing six computer manufacturers and three government agencies. In particular, the six computer manufacturers were Burroughs Corporation, IBM, Minneapolis-Honeywell (Honeywell Labs), RCA, Sperry Rand, and Sylvania Electric Products. The three government agencies were the US Air Force, the David Taylor Model Basin, and the National Bureau of Standards (Now NIST). This committee was chaired by a member of the NBS. An Intermediate-Range Committee and a Long-Range Committee were proposed at the Pentagon meeting as well. However although the Intermediate Range Committee was formed, it was never operational; and the Long-Range Committee was never even formed. In the end a sub-committee of the Short Range Committee developed the specifications of the COBOL language. This sub-committee was made up of six individuals:

• William Selden and Gertrude Tierney of IBM

• Howard Bromberg and Howard Discount of RCA

• Vernon Reeves and Jean E. Sammet of Sylvania Electric Products

This subcommittee completed the specifications for COBOL as the year of 1959 came to an end. The specifications were to a great extent inspired by the FLOW-MATIC language invented by Grace Hopper, and the IBM COMTRAN language invented by Bob Bemer.

The specifications were approved by the full Short Range Committee. From there, they were approved by the Executive Committee in January 1960, and sent to the government printing office, which edited and printed these specifications as Cobol 60. COBOL was developed within a six month period, and yet is still in use over 40 years later.