Minecraft Functions – Do Minecraft Functions Have Inputs and Outputs Like Conventional Functions?

You can use scoreboard in player selectors to find out which one they clicked. Usually this is done by either testfor or execute.

I recommend a 20 t/s clock to check these as soon as they click it. You don't have to use one, but it may help. great method to setup one.

In the case of testfor, it is actually not recommended to use it. You can't exactly distinguish which player clicked it, you just know that it was clicked. A better way is the execute method. Never-the-less, the command should look like this:

Testfor @a[score_test=1,score_test_min=1]

You will need a comparator to get if it succeeded to find it. You should also have a separate command block for each, then change the 1 to another number for each possible outcome.

In the case of execute: recommended method. You can use @p in the command part to target that specific player. Command as follows:

Execute @a[score_test=1,score_test_min=1] ~ ~ ~ <command>

For this, you should set their score of that to 0 as soon as the command is run, otherwise that command may be run twice.

I don't know why, but functions only work in prerelease 1. They don't even work in the finished update. You'll have to switch to prerelease 1 to use them.