samuz__15:
i really sorry for my ignorance. if i short them to ground, how i connect the analog input of voltage?
and thank you very much for your help and patience
What we are trying to say is that you do not have a problem, you just think you do. If you do not have anything wired up to a specific analog input pin then simply do not perform a analogRead() on that pin, so no problem with that correct?
If you do have a valid electrical signal wired to a analog input pin then you are free to perform analogRead() function on it and use it's value as you please in your program.
Does that answer your concerns?