Pascal (programming language)

Pascal (programming language)

 

Pascal is a historically influential imperative and procedural programming language, designed in 1968–1969 and published in 1970 by Niklaus Wirth as a small and efficient language intended to encourage good programming practices using structured programming and data structuring.
A derivative known as Object Pascal designed for object-oriented programming was developed in 1985.

History

Pascal, named in honor of the French mathematician and philosopher Blaise Pascal, was developed by Niklaus Wirth.
Before his work on Pascal, Wirth had developed Euler and ALGOL W and later went on to develop the Pascal-like languages Modula-2 and Oberon.
Initially, Pascal was largely, but not exclusively, intended to teach students structured programming A generation of students used Pascal as an introductory language in undergraduate courses. Variants of Pascal have also frequently been used for everything from research projects to PC games and embedded systems. Newer Pascal compilers exist which are widely used.
Pascal was the primary high-level language used for development in the Apple Lisa, and in the early years of the Macintosh. Parts of the original Macintosh operating system were hand-translated into Motorola 68000 assembly language from the Pascal sources. The typesetting system TeX by Donald E. Knuth was written in WEB, the original literate programming system, based on DEC PDP-10 Pascal, while applications like Total Commander, Skype and Macromedia Captivate were written in Delphi (Object Pascal).
Object Pascal (Embarcadero Delphi) is still used for developing Windows applications but also has the ability to cross compile the same code to Mac, iOS and Android. Another cross-platform version called Free Pascal, with the Lazarus IDE, is popular with Linux users since it also offers write once, compile anywhere development. CodeTyphon is a variant of Lazarus with more preinstalled packages and cross compilers.


Brief description

Wirth's intention was to create an efficient language (regarding both compilation speed and generated code) based on so-called structured programming, a concept which had recently become popular. Pascal has its roots in the ALGOL 60 language, but also introduced concepts and mechanisms which (on top of ALGOL's scalars and arrays) enabled programmers to define their own complex (structured) datatypes, and also made it easier to build dynamic and recursive data structures such as lists, trees and graphs. Important features included for this were records, enumerations, subranges, dynamically allocated variables with associated pointers, and sets. To make this possible and meaningful, Pascal has a strong typing on all objects, which means that one type of data cannot be converted or interpreted as another without explicit conversions. Similar mechanisms are standard in many programming languages today. Other languages that influenced Pascal's development were COBOL, Simula 67, and Wirth's own ALGOL W.
Pascal, like many programming languages of today (but unlike most languages in the C family), allows nested procedure definitions to any level of depth, and also allows most kinds of definitions and declarations inside subroutines (procedures and functions). This enables a very simple and coherent syntax where a complete program is syntactically nearly identical to a single procedure or function (except for the heading, which has one of these three keywords).
 pascal founder 
Niklaus Wirth


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