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Англійська мова для професійного спілкування (д....doc
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V. Answer the questions.

1. What is a machine code?

2. What can cause many errors?

3. What languages are called the first-generation languages?

4. Why are machine languages very tedious and exacting?

5. What does programming in machine languages require?

6. What makes machine language programming a difficult and error-prone task?

7. Why were assembler languages developed?

8. Why are they called symbolic languages?

9. What are advantages of assembler language?

10. What are disadvantages of assembler language?

11. What instructions do high-level languages use?

12. What are advantages and disadvantages of high-level languages?

Read the text.

Icon is a high-level programming language with extensive facilities for processing strings and structures. Icon has several novel features, including expressions that may produce sequences of results, goal-directed evaluation that automatically searches for a successful result, and string scanning that allows operations on strings to be formulated at a high conceptual level. Icon also provides high-level graphics facilities. Icon emphasizes high-level string processing and a design philosophy that allows ease of programming and short, concise programs. Storage allocation and garbage collection are automatic in Icon, and there are few restrictions on the sizes of objects. Strings, lists, and other structures are created during program execution and their size does not need to be known when a program is written. Values are converted to expected types automatically; for example, numeral strings read in as input can be used in numerical computations without explicit conversion. Icon has an expression-based syntax with reserved words; in appearance, Icon programs resemble those of Pascal and C. Although Icon has extensive facilities for processing strings and structures, it also has a full repertoire of computational facilities. It is suitable for a wide variety of applications. Some examples are:

  • text analysis

  • text editing

  • document formatting

  • artificial intelligence

  • expert systems

  • rapid prototyping

  • symbolic mathematics

  • text generation

  • data laundry.

Fourth-Generation Languages

The term fourth-generation language describes a variety of programming languages that are more nonprocedural and conversational that prior language. These languages are called fourth-generation languages (4GLs) to differentiate them from machine languages (first generation), assembler languages (second generation), and high-level languages (third generation).

Most fourth-generation languages are nonprocedural languages that encourage users and programmers to specify the result they want, while the computer determines the sequence of instructions that will accomplish those results. Users and programmers no longer have to spend a lot of time developing the sequence of instructions the computer must follow to achieve a result. Thus, fourth-generation languages have helped simplify the programming process. Whereas a fourth-generation language program must follow a specific set of rules and syntax, a natural program does not. A natural language, sometimes called a fifth-generation language, is a type of query language that allows the user to enter requests that resemble human speech. Research and development activity in artificial intelligence is developing programming languages that are as easy to use as ordinary conversation in one’s native tongue.

Advantages and Disadvantages. There are major differences in the ease of use and technical sophistication of 4GL products. For instance, INTELLECT and English Wizard are examples of natural query languages that impose no rigid grammatical rule, while languages like SQL requires concise structured statements. However, the ease of use of 4GLs is gained at the expense of some loss in flexibility. It is frequently difficult for an end user to override some of the prespecified formats or procedures of 4GLs. In addition, the machine languages code generated by a program developed by a 4GL is frequently much less efficient (in terms of processing speed and amount of storage capacity needed) that a program written in a languages like COBOL. Major failures have occurred in some large transaction processing applications programmed in a 4GL. These applications were unable to provide reasonable response times when faced with a large amount of real-time transaction processing and end user inquiries. However, 4GLs have shown great success in business applications that do not have a high volume of transaction processing.

Comments:

nonprocedural language не процедурна мова//мови програмування, які

ґрунтуються не на послідовно виконуваних

операторах, а на описі набору (бази) фактів і

відношень (правил), за якими виводиться відповідь

на поставлене запитання

concise короткий, стислий; чіткий, виразний

to override скасовувати; відхиляти

SQL Structured мова структурованих запитів, мова SQL

Query Language мова запитів