The C preprocessor and Jensen's device

Abstract

When teaching a course in Programming Languages, one generally discusses dif­ ferent methods for passing parameters to subprograms. Most students, being some­ what proficient in Pascal, have a basic understanding of the difference between passing parameters by value and passing them by address. Those who have pro­ grammed in C usually have acquired a better understanding of this difference through experience, since parameters are all passed by value, so that addresses must be passed explicitly when one wants to pass by address. Other parameter passing methods are new to these stu­ dents. The advantages of being able to pass parameters by result are worth discussing since most students under­ stand parameters which are used as out-