The Pl/I Programming Language (Classic Reprint)

Excerpt from The Pl/I Programming Language\nFortran's rigid rules for program formatting. The notion of block structure was taken from Algol 60, while pl/i structures were taken from the record descriptions of Cobol. However, a great many features were added to pl/i that have no counter part in its ancestor languages. An example of a pl/i program is given in Figure l. A program is written as a sequence of external procedures, which are defined in such a way that they can be compiled separately and then linked together when the program is executed. Within an external procedure, there can be internal procedures.