How can I check to see if the pipe coming out of the floor has a p trap in it all ready?

Where is this this "P" trap located? If you are on a Conve. Floor { one with floor joist} Then crawl under the house to the location and you will be able to see: Carry a flashlight with you. If you are on a concrete slab and you can get to a open end close to the floor as possible look down inside with a flashlight. A expen. Plumber that has done pushing asewer rod threw a sewer pipe can tell by feel alone that he or she is going threw a "p" trap,45,90 or what: Good lUCK HOPE I HAVE HELPED: