Iteration with the for loop

The first type of iteration we will look at is the for loop. This is a kind of loop when we, in one way or the other, know how many times we want to repeat something. This can be a fixed number of times, such as iterating over a list using the days of the week. We know it is always 7. It can also be that we have values in an array. We might not know precisely how many items there are in the array at any given time; however, as we will see, there are ways to ask the array how many objects it is currently holding.

When using a for loop, we will work with a variable that keeps track of how many times we have iterated. We can decide what value this variable shall start on. It is this variable that helps us to know when to stop iterating. Let's look at an example:

for i = 0 to 10
    …
end_for

Here, we create (or declare, as a programmer would say) a variable called i. The name, i, is frequently used as the name for this...