Classification of High-Level Languages

High-level languages are commonly classified as procedure-oriented, functional, object-oriented, or logic languages. The most common high-level languages today are procedure-oriented languages. In these languages, one or more statements are grouped together into a program module, or procedure, and given a name such as “procedure A”. If the same procedure is needed elsewhere in the program, a simple statement can be used to refer back to it. Procedural languages allow programs to be shorter and easier for the computer to read, but they require the programmer to design each procedure to be general enough to be used in different situations.

Functional languages treat procedures like mathematical functions and allow them to be processed like any other data in a program. This allows a much higher and more rigorous level of program construction. Functional languages also allow variables to be given values only once. This simplifies programming by reducing the need to be concerned with the extract order of statement execution. Many of the ideas from functional languages have become key parts of many modern procedural languages.

Object-oriented languages are outgrowths of functional languages. In object-oriented languages, the code used to write the program and the data processed by the program are grouped together into units called objects. Objects are further grouped into classes, which define the attributes object must have. A simple example of a class is the class Book. Objects within this class might be Novel and Short Story. Objects also have certain functions associated with them, called methods. The computer accesses an object through the use of one of the object’s methods. The method performs some action to the data in the object and returns this value to the computer. Classes of objects can also be further grouped into hierarchies, in which objects of one class can inherit methods from another class. The structure provided in object-oriented languages makes them very useful for complicated programming tasks.

Logic languages use logic as their mathematical base. A logic program consists of sets of facts and if-then rules, which specify how one set of facts may be deducted from others, for example: If the statement X is true, then the statement Y is false. Many artificial intelligence programs are written in such languages.

III. Assignments:

ü Name the types of programming languages. What is the difference between them?

ü How can high-level languages be classified? Why is such classification used?

ü Give the example of high- and low-level languages.