Rewritten ever so slightly to follow the rule that you should place the most likely condition at the top of a list of conditionals. Also took of the second condition as a boolean only has two values so you don't need to check it twice. Also added semicolons because that's what I do. Also added a space after each
if because damn it, that's how God intended it to be (He also intended programmers to use tabs instead of spaces but I didn't fix that).
Code:
new bool:g_MyFunctionUsed[33]; // Global Value.
public MyFunction(id)
{
if (g_MyFunctionUsed[id])
{
console_print(id, "You have already activated this command.");
}
else
{
g_MyFunctionUsed[id] = true;
}
}