Bad alternator on Mitsubishi Mirage?

My friend's 1999 Mitsubishi Mirage has been idling rough for the last couple days, (after filling up with gas) and has occasionally been stalling while idling - I ume it was bad gas. Now (I ume it's unrelated) it fails to start - at first it clicked, now it doesn't do anything. The battery is only a couple months old. I checked the connection, poured coke on it, etc. I'm uming the only thing left is the alternator (or rarely, a draining short) - am I correct?