How can I use a parameter from a callback?

I'm new at SA-MP scripting. And I'm wondering if this is possible to do. If I have a variable like this.

Code:

---

new Variable[MAX_PLAYERS];

---

Then I want to use that variable in a callback but I don't know how to mention a parameter like playerid or killerid. Is it possible that if the callback is called the playerid parameter is mentioned which will check the variable. If it's 0 or 1.



Sorry If you're confused.