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Pascal

Pascal. 1130379007 Suhua Lei. NIKLAUS WIRTH. Known for Algol W, Euler,  Pascal , Modula,  Modula-2,Oberon,  Oberon-2,Oberon-07,  Oberon System. BORN February 15, 1934  (age 80) Winterthur, Switzerland Citizenship Switzerland.

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Pascal

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  1. Pascal 1130379007 Suhua Lei

  2. NIKLAUS WIRTH Known for Algol W, Euler, Pascal,Modula, Modula-2,Oberon, Oberon-2,Oberon-07, Oberon System BORN February 15, 1934 (age 80)Winterthur, Switzerland Citizenship Switzerland Notable Awards SIGPLAN Programming Languages Achievement AwardFellow of the Computer History MuseumMarcel Benoist Prize (1989) Turing Award

  3. A Famous Book Algorithms Data Structures Programs

  4. Who influences its birth? 1958 ALGOL58 Algol Doesn’t Have Enough Data Types! 1960 ALGOL60 1966 ALGOL W 1970 PASCAL

  5. Data Types

  6. Data Types • Complex types can be constructed from simple types:

  7. Programming Paradigm • Imperative, procedural • the flow of control is structured into standard statements, usually without 'goto' commands. • Object Pascal support multiple paradigms • Programs written in Object Pascal can be purely procedural, or purely object-oriented, or contain elements of both paradigms

  8. Type system • It’s statically typed • Its type system has been described as "too strong" • Eg: the size of an array or string is part of its type, making some programming tasks difficult • Java > Pascal > C • It’s safe except two conditions • Function as parameter • Using unsigned variant record type

  9. Compilers

  10. Example: hello world

  11. Example: pi

  12. Conclusion：characteristic • 严格的结构化形式； • 丰富完备的数据类型； • 运行效率高； • 查错能力强。

  13. Conclusion：disadvantages • 传统PASCAL的标准库中缺乏对网络编程的支持，并且仅通过自带的graph单元难以实现较好的图形界面（GUI），这些缺点大多需要嵌入汇编语言代码才能得到解决，缺乏与机器语言的接口。 • 与面向对象的语言相比，不利于大型软件的开发。 • 推广了C语言的Brian Kernighan在1981年《Why Pascal Is Not My Favourite Programming Language》对Pascal提出了严厉的抨击。

  14. Applications • GCC，Gnu C编译器，最初是用Pascal的一种方言Pastel编写的 • Pascal是Apple Lisa和早期Mac开发使用的高级语言 • 流行的排版系统TeX是由高德纳使用基于DECPDP-10 Pascal的最初文学编程系统WEB编写的 • Object Pascal仍然广泛用于开发像Skype这样的Windows应用 • … …

  15. Delphi的没落 • Object Pascal并没有像C/C++那样成为业内标准 • 人才流失，与内部决策失误。Delphi之父AndersHejlsberg离开Borland去了微软，导致Delphi的编译器有三年的时间无人敢动，因为AndersHejlsberg完全使用汇编实现的编译器，无人能够看懂。 • 市场转变开发市场现在更注重B/S结构的应用，桌面应用正在大幅减少，Delphi显然不是一个理想的WEB开发语言。

  16. Thank you !

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