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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.
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