Derived Types

Abstract

There are many situations in programming where it is desirable that a programmer be permitted to group a collection of related pieces of data, possibly of different types, under a single name. Several languages, including COBOL, PL/I, C, Pascal, and Ada, provide this capability. But despite widespread agreement as to the usefulness of this capability in organizing complicated data, it is supported in only a few FORTRAN 77 implementations (notably Digital’s). The terminology used in dealing with a data aggregate containing different types is not uniform throughout the software world, and both the term “record” and the term “structure” have been associated with such a collection. The Fortran 90 standard employs only the latter term in this context. And while the Fortran 90 structure is conceptually similar to such data aggregates in other languages and in pre-1992 FORTRAN 77 implementations, the Fortran 90 standard embraces some differences in vocabulary, syntax, and rules of usage.