ActionScript: The Definitive Guide

Loop Terminology

In the previous section we encountered several new terms. Let’s look at these more formally, so that you’ll understand them well when working with loops:

Initialization

The statement or expression that defines one or more variables used in the test expression of a loop.

Test expression

The condition that must be met in order for the substatements in the loop body to be executed. Often called a condition or test, or sometimes, control.

Update

The statements that modify the variables used in the test expression before a subsequent test. A typical update statement increments or decrements the loop’s counter.

Iteration

One complete execution of the test expression and statements in the loop body. Sometimes referred to as one loop or one pass.

Nesting or nested loop

A loop that contains another loop so that you can iterate through some sort of two-dimensional data. For example, you might loop through each row in a column for all the columns in a table. The outer or top-level loop would progress through the columns, and the inner loop would progress through the rows in each column.

Iterator or index variable

A variable whose value increases or decreases with each iteration of a loop, usually used to count or sequence through some data. Loop iterators are often called counters. Iterators are conventionally named i, j, and k or sometimes x, y, and z. In a series of nested loops, i is usually the iterator of the top-level loop, j is the iterator of the first nested loop, ...