Moreover modular procedure blocks and other features

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Unformatted text preview: C STARTS HERE *) BEGIN SUM := 0; FORI:= 1 TO 10 DO BEGIN READ (N); SUM := SUM + N; END; WR1TELN ('THE SUM OF GIVEN NUMBERS=', SUM); END; PL/1 PL/1 stands for Programming Language One. It was designed by IBM in 1964. The main objective of the designers was to design a universal programming language that could be used for programming any kind of application. Note that during those days, FORTRAN was used for scientific applications and COBOL was used for business applications. To meet the objective mentioned above, PL/1 was designed to have the following features: 1. Features similar to COBOL for programming business applications. 2. Features similar to FORTRAN for programming scientific applications. 3. Other features such as string manipulation, list processing, pointer data type, concurrent execution of tasks and exception handling, for systems programming and other types of applications. With all these features, PL/1 became one of the most versatile and most powerful of the programming languages. However, it could not become the most commonly used language because with so many features included in it, it also became a sophisticated language to learn and use. It is enormous by any standards and is not easy to learn in its totality. Furthermore, the complexity of the language makes a compiler and support packages for the full language quite large. Because of its size and heritage, the language has so far been available primarily on IBM systems and is not very widely used or accepted. A PL/1 standard was produced by ANSI in the year 1976. A subset of this full standard, known as PL/l-G was also made available for use with personal computers. A PL/1 program to compute and print the sum of 10 numbers is given in Figure 12.22. It can be seen from this example, that the basic element of a PL/1 program is a statement. Each statement is terminated with a semicolon (;) and several statements may be combined to form a procedure. A procedure may represent an entire small program (as in this example) or a block or module of a more complex program. Because of its modular structure, a beginner needs only a small part of the language in order to write programs for a particular type of application. Moreov...
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