Text 2. PROGRAMMING LANGUAGES

Let's assume that we have studied the problem, designed a \

logical plan (our flowchart or pseudocode), and are now ready \

to write the program instructions. The process of writing pro- j

gram instructions is called coding. The instructions will be writ-.

ten on a form called a coding form.^The instructions we write ■

will be recorded in a machine-readable form using a keypunch, ^;

key-to-tape, or key-to-disk, or entered directly into computer;
memory through a terminal keyboard.

The computer cannot understand instructions written in just ■ v

any old way. The instructions must be written according to a set!

of rules. These rules are the foundation of a programming Ian- j

guage. A programming language must convey the logical steps ■*

of the program plan in such a way that the control unit of the \

CPU can interpret and follow the instructions. Programming j

languages have improved throughout the years, just as comput- I.

er hardware has improved. They have progressed from machine- \

151_______________________ Unit 11. Computer Programming

oriented languages that use strings of binary Is and 0s to prob­lem-oriented languages that use common mathematical and/or English terms.

There are over 200 problem-oriented languages. The most common of them are COBOL, FORTRAN, PL/I, RPG, BA­SIC, PASCAL.

COBOL

COBOL was the most widely used business-oriented pro­gramming language. Its name is an acronym for Common Јlisi-ncss-Oriented Zanguage. COBOL was designed to solve prob­lems that are oriented toward data handling and input-output operations. Of course, COBOL can perform arithmetic opera­tions as well, but its greatest flexibility is in data handling. CO­BOL also was designed as a self-documenting language. Self-documenting languages are those that do not require a great deal of explanation in order to be understood by someone reading the program instructions. The self-documenting aspect of CO­BOL is made possible by its sentencelike structure and the very generous maximum symbolic field-name length of 30 charac­ters. With a field-name length of up to 30 characters, the name can clearly identify the field and its purpose.