Declaring local variables where they belong, logically speaking We discuss the placement of local variable declarations. Generally, the declarations should go where they be-long, logically speaking, and this usually means placing them as close to their first use as possible. Let’s look at an example that illustrates this. Here is a procedure to sort an array segment b[0. .n] using an algorithm called selection sort . We have not discussed arrays in this course, but you have seen them in another programming language. In the first para-meter declaration, you see how to declare b to be a one-dimensional array. Just after the declaration of temp and j is a comment that states the invariant of the main loop —this is simply a picture that holds before and after each iteration of the loop, and we display the information as a pic-ture down below. The picture says that the segment b[0. .k-1] is sorted and that all of its elements are at most those in the second segment, that’s what we mean by the signs
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This note was uploaded on 07/07/2008 for the course CS 101 taught by Professor Gries during the Spring '08 term at Cornell.