Thursday, 29 January 2015

45 TOP Pascal Programming Interview Questions and Answers(Part1)

1. Why is the name pascal?
Pascal was named after the French mathematician Blaise Pascal, who created a calculating machine (not a true computer).

2. What is standard Pascal?
Pascal is one of a series of languages put forth by one of the most prolific computer language creators, Niklaus Wirth, a professor at Institut fur informatik, ETH, Zurich, Switzerland. Professor Wirth participated in various versions of Algol, a language put forth by international cooperation that introduced the basic concepts of structured programming to the world. Wirth terms Pascal as a descendant of Algol 60 (for Algol, 1960 standard). The "official" descendant of Algol 60 was Algol 68, famous for having assignment as an expression operator (a basic feature of the later language C). Wirth felt that the design committee for Algol, after Algol 60, was losing focus and creating an unnecessarily complex language.
While Algol W has had it's fans, the language Pascal was considered to be a new high of consistent language design. The first draft of Pascal was created in 1968. The first compiler was operational in 1970, and the language was generally published in 1971. In 1973, after two years of testing and use, the language was revised into it's final form. That was detailed by "The Pascal User Manual and Report".

3. What is the history of Pascal?
Pascal is in the Algol family of languages. Algol, whose first version was called IAL or "International Algebraic Language", was the first language created by international committee. The resulting language was rather odd for its time. The committee had the goal of designing a unified computer language, but also saw Algol as a way to cleanly express computer algorithms, and so was not directly concerned with creating a practical language for compilation. That is, the language would serve a purpose even if it was only used for publishing algorithms, not running them.
This resulted in Algol not having many data types, or built in I/O. Also, Algol was generally free of the limits common to programming languages of that time, such as number of array dimensions. One of the goals of Algol was for it to be as close to mathematical notation as possible. In particular, Algol used a special operator for assignment, ':=', because '=' had a different meaning in mathematics.

4. What are the different Pascal standards?
The original Pascal standard was an unofficial standard documented by the author, Niklaus Wirth, in "The Report". The first official standard was ISO 7185 issued in 1983. This was followed by the extended standard, ISO 10206, in 1990. Another standard was the Object-Oriented Extension to Pascal. However, this standard was never finished, and was basically abandoned for lack of interest.

5. What is the current status of Pascal standards?
In 1989, ISO 7185 was revised to correct various errors and ambiguities found in the original document. This resulted in ISO 7185:1990.
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