The anatomy of a loop

An iterative loop always starts with the for keyword. It has three important sections:

• Where to start

• Where to end

• What to do after every loop finishes

In this case, we start by declaring an iterator variable called i of type int (integer), and set that iterator i to zero.

var i:int = 0

Next, we say that we're going to loop as long as the value of i is less than (<) the value of rows. Because we've already set rows to 4, this code will loop four times.

i<rows

In the third section, we increase the value of i by one. Here's how the interpreter chews through our loop:

1. Set an integer variable called i to 0.

2. Check to see if i is less than rows (4). 0 is less than 4, so let's go!

3. Run the code inside the loop.

4. When we're finished, increase i by one. (i++). i is now 1.

5. Check again to see if i is less than rows (4). 1 is less than 4, so let's keep going.

6. Run the code inside the loop.

7. Repeat until we increase i to 4 on the fourth loop.

8. Because i is no longer less than rows (4), stop repeating...