music PL/I

Programming Language One

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    nature: procedural language

    history: Work on PL/I started in 1963. PL/I (Programming Language One) was created in 1964 at IBM’s Hursley Laboratories in the United Kingdom. PL/I was intended as an all-purpose langauge to combine the scientific abilities of FORTRAN with the business capabilities of COBOL, plus additional facilities for systems programming. Also borrows from ALGOL 60. Originally called NPL, or New Programming Language. Introduces storage classes (automatic, static, controlled, and based), exception processing (On conditions), Select When Otherwise conditional structure, and several variations of the DO loop. Numerous data types, including control over precision.

Hello World example



    format: free form; block structured

lexical elements

    source code character set: PL/I has a 60 character source code character set: an extended alphabet of 29 characters ( $ @ # A B C D E F G H I J K L M N O P Q R S T U V W X Y Z ), the 10 decimal digits ( 0 1 2 3 4 5 6 7 8 9 ), and 21 special characters ( blank = + - * / ( ) , . ' % ; : ¬ & | > < _ ? ). Some kind of line break or record separator may be used with some input devices.

    alternative characters: A special 48 character set is available for older hardware. In the 48 character set, the at sign (@), pound sign (#), break (underscore _), and question mark (?) characters are dropped. 12 operators are reserved keywords (and must be surrounded on both sides by one or more space characters):

operation60 character set48 character set
greater than>GT
greater than or equal>=GE
less than<LT
less than or equal<=LE
not less than¬<NL
not greater than¬>NG
not equal¬=NE
points to->PT

    A PROCESS statement of the following form must be used specify the 48-character option:

        *PROCESS CHARSET (48),.

    If the 48 character set is specified, the programmer may use any character from the 60 character set except pound (#), at sign (@), question mark (?), or underscore (_). If the 60 character set (the default) is used, none of the special operators are reserved words and can not be used for their special meanings.

further reading: books:

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    Pl/1 Structured Programming; 3rd edition; by Joan Kirkby Hughes; John Wiley & Sons; June 1986; ISBN 0471837466; paperback; 639 pages; $70.60

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    Last Updated: October 2, 2007

    Created: January 2, 1999

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