A proposal for a Fortran loop construct

Abstract

The block IF, ELSE IF, ELSE, and END IF statements [1] have been added during revision of the draft proposed ANS FORTRAN [2]. There have been several suggestions to add new looping constructs, such as DO WHILE or DO UNTIL. There are at least two reasons for not adopting these proposals at this time:1. The DO statement is already available in FORTRAN. Although the syntax may not be elegant by current standards, it is possible to construct loops and leave them using the GO TO statement.2. The constructs proposed only handle special cases of what is needed: a convenient way of leaving from any point in a loop and leaving any level of nesting of loops.Presumably, control structures will be one of the first items discussed when and if work is begun on another revision of the FORTRAN standard. The purpose of this note is to generate some discussion and perhaps some implementations, so that decisions to include other control structures will be based on more experience than is available now. Only loop constructs will be discussed.