So far, we’ve stored just one variable. But, we can also store lists of variabled.

The code looks like this:

when this sprite clicked
say (item (i) of [Catch Phrases v]) for (2) seconds
change [i v] by (1)

The problem here is that he gives as soon as i is greater than the number of items in the list. We could write some complicated logic or we could use our good friend the modulo operator.

We might try something like this:

when this sprite clicked
say (item ((i) mod (4)) of [Catch Phrases v]) for (0.5) seconds
change [i v] by (1)

The problem is that occasionally, this will be zero and this still won’t work. We can adjust things a little bit.

when this sprite clicked
say (item (((i) mod (4)) + (1)) of [Catch Phrases v]) for (0.5) seconds
change [i v] by (1)

when @greenFlag clicked
set [i v] to [0]

Now, we’ll start at 0 and always add 1 to the result of the module. And now everything works as expected.

One Further Improvement

What if we add more things to the list? That number 4 is hard coded. In programming, we call this a magic number. What is the meaning of 4? Well, it’s the length of the list, right?

We just use that instead.

when this sprite clicked
say (item (((i) mod (length of [Catch Phrases v]::data)) + (1)) of [Catch Phrases v]) for (0.5) seconds
change [i v] by (1)

when @greenFlag clicked
set [i v] to [0]

Here is what we have now.

Your Turn

• Each can have it’s own list.
• They can broadcast back and forth.
• i could be a shared variable or you could try it unique to each sprite.

Now, we’ll talk about falling.