Introduction to Subroutines

Abstract

The aims of this chapter are:

• to consider some of the reasons for the inclusion of subroutines in a programming language;

• to introduce with a concrete example some of the concepts and ideas involved with the definition and use of subroutines:

  • the INTERFACE statement and interface blocks;

  • parameters;

  • the INTENT attribute for parameters;

  • the CALL statement;

  • scope of variables;

  • local variables and local variables and the SAVE attribute;

  • the use of parameters to report on the status of the action carried out in the subroutine;

A man should keep his brain attic stacked with all the furniture he is likely to use, and the rest he can put away in the lumber room of his library, where he can get at it if he wants.

Sir Arthur Conan-Doyle, Five Orange Pips.