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1、计算机专业英语,主讲教师：,2,能力提高篇,3,能力提高篇,Learning Scenarios 2 Computer Programming,Words & Expressions Text A: Milestones of Programming Languages Text B: Types in the C Programming Language Practice Reading Material,5,Words & Expressions - 1,6,Words & Expressions - 2,7,Words & Expressions - 3,8,Words & Expres
2、sions - 4,9,Text A: Milestones of Programming Languages,Para 1. The first programming languages predate the modern computer. At first, the languages were codes. The Jacquard loom, invented in 1801, used holes in punched cards to represent sewing loom arm movements in order to generate decorative pat
3、terns automatically. During a nine-month period in 1842-1843, Ada Lovelace translated the memoir of Italian mathematician Luigi Menabrea about Charles Babbages newest proposed machine, the Analytical Engine. With the article, she appended a set of notes which specified in complete detail a method fo
4、r calculating Bernoulli numbers with the Engine, recognized by some historians as the worlds first computer program. Herman Hollerith realized that he could encode information on punch cards when he observed that train conductors encode the appearance of the ticket holders on the train tickets using
5、 the position of punched holes on the tickets. Hollerith then encoded the 1890 census data on punch cards.,10,Para 2. The first computer codes were specialized for their applications. In the first decades of the 20th century, numerical calculations were based on decimal numbers. Eventually it was re
6、alized that logic could be represented with numbers, not only with words. For example, Alonzo Church was able to express the lambda calculus in a formulaic way. The Turing machine was an abstraction of the operation of a tape-marking machine, for example, in use at the telephone companies. Turing ma
7、chines set the basis for storage of programs as data in the von Neumann architecture of computers by representing a machine through a finite number. However, unlike the lambda calculus, Turings code does not serve well as a basis for higher-level languagesits principal use is in rigorous analyses of
8、 algorithmic complexity.,Text A: Milestones of Programming Languages,11,Para 3. Like many “firsts“ in history, the first modern programming language is hard to identify. From the start, the restrictions of the hardware defined the language. Punch cards allowed 80 columns, but some of the columns had
9、 to be used for a sorting number on each card. FORTRAN included some keywords which were the same as English words, such as “IF“, “GOTO“ (go to) and “CONTINUE“. The use of a magnetic drum for memory meant that computer programs also had to be interleaved with the rotations of the drum. Thus the prog
10、rams were more hardware-dependent.,Text A: Milestones of Programming Languages,12,Para 4. To some people, what was the first modern programming language depends on how much power and human-readability is required before the status of “programming language“ is granted. Jacquard looms and Charles Babb
11、ages Difference Engine both had simple, extremely limited languages for describing the actions that these machines should perform. One can even regard the punch holes on a player piano scroll as a limited domain-specific language, albeit not designed for human consumption.,Text A: Milestones of Prog
12、ramming Languages,13,Para 5. Another milestone in the late 1950s was the publication, by a committee of American and European computer scientists, of “a new language for algorithms“; the ALGOL 60 Report (the “ALGOrithmic Language“). This report consolidated many ideas circulating at the time and fea
13、tured two key language innovations: nested block structure: code sequences and associated declarations could be grouped into blocks without having to be turned into separate, explicitly named procedures; lexical scoping: a block could have its own private variables, procedures and functions, invisib
14、le to code outside that block, i.e. information hiding. Another innovation, related to this, was in how the language was described: a mathematically exact notation, Backus-Naur Form (BNF), was used to describe the languages syntax. Nearly all subsequent programming languages have used a variant of B
15、NF to describe the context-free portion of their syntax.,Text A: Milestones of Programming Languages,14,Para 6. Algol 60 was particularly influential in the design of later languages, some of which soon became more popular. The Burroughs large systems were designed to be programmed in an extended su
16、bset of Algol. Algols key ideas were continued, producing ALGOL 68: syntax and semantics became even more orthogonal, with anonymous routines, a recursive typing system with higher-order functions, etc.; not only the context-free part, but the full language syntax and semantics were defined formally, in terms of Van Wijngaarden grammar, a formalism designed specifically for this purpose. Algol 68s many little-used language features (e.g. concurrent and parallel blocks) and its c
