Programming Languages and Functions

The use of existing and new programming languages have extended the capabilities of the Web. Here are a group of the more common languages and functions in use on the Web today.

CGI, Active Server Pages: CGI (Common Gateway Interface) refers to a specification by which programs can communicate with a Web server. A CGI program. Or script, is any program designed to accept and return data that conforms to the CGI specification. The program can be written in any programming language, including C, Perl, and Visual Basic Script. A common use for a CGI script is to process an interactive form on a Web page. For example, you might fill out a form ordering a book through Interlibrary Loan. The script processes your information and sends it to a designated e-mail address in the Interlibrary Loan department.

Java/Java Applets: Java is probably the most famous of the programming languages of the Web. Java is an object-oriented programming language similar to C++. Developed by Sun Microsystems, the aim of Java is to create programs that will be platform independent. The Java motto is “Write once, run anywhere”. A perfect Java program should work equally on a PC, Macintosh, Unix, and so on without any additional programming. This goal has yet to be realized. Java can be used to write applications for both Web and non-Web use. Web-based applications are usually in the form of Java applets. These are small Java programs called from an HTML page that can be downloaded from a Web server and run on a Java-compatible Web browser. A few examples include live newsfeeds, moving images with sound, calculators, charts and spreadsheets, and interactive visual displays.

JavaScript/JScript: JavaScript is a programming language created by Netscape Communications. Small programs written in this language are embedded within an HTML page. Examples of JavaScript include moving tickers, drop-down menus, real-time calendars and clocks, and mouse-over interactions. JScript is a similar language developed by Microsoft and works with the company’s Internet Explorer browser.

VRML: (Virtual Reality Modeling Language) allows for the creation of three- dimensional worlds. These may be linked from Web pages and displayed with a VRML viewer. One of the most interesting aspects of VRML is the option to “enter” the world and control your movements within the world.

XML: (eXtensible Markup Language) is a Web page creation language that enables designers to create their own customized tags to provide functionality not available with HTML. XML is a language of data structure and exchange, and allows developers to separate form from content. At present, this language is little used as Web browser are only beginning to support it.

Divide the text into the logical parts and give a title to each one.

Put questions to the text.

Discuss it with your groupmates.

Unit 4

Text Study: Programming Languages.

Additional Text: SIMULA, SMALLTALK, AND EIFFEL.

Grammar: Revision of the Module V.

Text Study

I. Pre-reading Exercises

1. Repeat the words in chorus:

To compile, to interpret, an acronym, features, consequently, to support, suitable, compiler, efficient, considerable, power, responsibility, to revise, acceptable, errors, superficial, level, syntactically, ambiguous.

2. While reading the text you will come across a number of international words. Try to guess what Ukrainian words they remind of you:

To transform, algebraic, formulae, phrases, commercial, algorithmic, portable, peripheral, to manipulate, specific, registers, a dialect, abstract, technique, natural, grammatical, information.

3. Pay attention to some grammatical points:

1) Computers can deal with different kinds of problems if they are given the right instructions for what to do. 2) Instructions are first written in one of the high-level languages, e.g. FORTRAN, COBOL, ALCOL, PL/I, PASCAL, BASIC, or C., depending on the type of problem to be solved. 3) A program written in one of these languages is often called a source program. 4) This language is used for solving scientific and mathematical problems. 5) C was designed to be a language that would be suitable for writing system's software, like the core parts of an operating system. 6) The code generated by the compiler had to be very efficient if the language was to be used in this way. 7) Consequently, in some respects the language is simpler than other Algol family languages that have retained the relatively complex nested program structures. 8) Programming languages have grammatical rules that need to be learnt, just as natural languages do.

II. Reading

Read the text and be ready to find in the text the answers to the following questions:

· What programming languages do you know?

· Why cannot we make jokes in computer languages?

Programming Languages

Computers can deal with different kinds of problems if they are given the right instructions for what to do. Instructions are first written in one of the high-level languages, e.g. FORTRAN, COBOL, ALCOL, PL/I, PASCAL, BASIC, or C., depending on the type of problem to be solved. A program written in one of these languages is often called a source program, and it cannot be directly processed by the computer until it has been compiled, which means interpreted into machine code. Usually a single instruction written in a high-level language, when transformed into machine code, results in several instructions. Here is a brief description of some of the many high-level languages:

FORTRAN acronym for FORmula TRANslation. This language is used for solving scientific and mathematical problems. It consists of algebraic formulae and English phrases. It was first introduced in the United States in 1954.

COBOL acronym for Common Business-Oriented Language. This language is used for commercial purposes. COBOL deals with problems that do not involve a lot of mathematical calculations. It was first introduced in 1959.

ALGOL acronym for Algorithmic Language. Originally called IAL which means International Algebraic Language. It is used for mathematical and scientific purposes. ALGOL was first introduced in Europe in 1960.

PL/I Programming language I. Developed in 1964 to combine features of COBOL and ALGOL. Consequently, it is used for data processing as well as scientific applications.

BASIC acronym for Beginner’s All-purpose Symbolic Instruction Code. Developed in 1965 at Dartmouth College in the United States for use by students who require a simple language to begin programming.

C developed in the 1970s to support the UNIX operating system. C is a highly portable general-purpose language. C was designed to be a language that would be suitable for writing system's software, like the core parts of an operating system. The code generated by the compiler had to be very efficient if the language was to be used in this way. Anything a compiler would have difficulties with was dropped. Consequently, in some respects the language is simpler than other Algol family languages that have retained the relatively complex nested program structures. If C was to be used for writing things like "device driver code" (the code that actually interacts with the peripheral controllers), then it had to allow the programmer get down the hardware level and manipulate bits in specific registers and in particular memory addresses. This gives the programmer considerable power, and lots of responsibility.

C++ started as a dialect of C around about 1980, it has been revised twice since then. But they are still very similar languages (in fact, a correct C program should be acceptable to a C++ compiler). The C++ language aimed to achieve three things: to be a better C; to support "abstract data types"; to permit the use of a programming technique known as "object oriented programming" (OOP). C++ was designed to permit more compile time checking and also to offer alternatives to various features of C that were known to be common sources of programming errors.

Other such languages are APL (developed in 1962), PASCAL (named after Blaise Pascal and developed in 1971), and LISP and PROLOG, both of which are used for work in artificial intelligence. LOGO is a development of LISP which has been used to develop computer based training packages.

At a superficial level, programming languages and natural languages are similar. Programming languages have grammatical rules that need to be learnt, just as natural languages do. At the same level, computers can ‘’understand’’ and ‘’communicate with’’ humans through programming languages: superficial interaction is possible. However, programming languages are data-free and therefore contain no information in themselves. The information is contained in the data which is processed, but is independent of the language which is used to write the commands to proceed it. The sole purpose of a programming language is to give instructions to a computer, which - providing they are syntactically correct - will be executed. A syntactically correct statement in a programming language has only one interpretation. By definition, it cannot be ambiguous. You cannot make jokes in computer languages.

Vocabulary Notes

a source program – вхідна, початкова програма

a purpose – мета, ціль; the sole purpose – єдина мета

to support [sq'pLt] – підтримувати, допомагати

a compiler – компілятор, програма-компілятор; compile time – час компіляції, час роботи компілятора; to compile – вибирати інформацію, збирати матеріал, компілювати програму

to retain – тримати, акумулювати, тримати в пам’яті

а peripheral controller – периферійний контролер

considerable – значний, важливий

to revise – перевіряти, виправляти

acceptable [qk'septqbl]– допустимий

superficial ["sju:pq'fIS(q)l]– зовнішній, поверхневий

interaction – взаємодія, взаємозв’язок

syntactically [sIn'txktIklI]– синтаксично

ambiguous [xm'bIgjuqs] – двозначний, сумнівний

to make jokes – шуткувати

to deal with – мати справу з

to depend on – залежити від

a source – джерело

to process ['preuses] – обробляти

brief [brJf] – короткий

a description – опис

to introduce – вводити, представляти

consequently ['kOnsIkwqntlI]– отже, отож

nested structure ['strAktSq] – гніздова (вкладена структура)

Comprehension