It also depends on how long and how frequently you've smoked. If it was one hit, one time only and ever, should be out of your system for a urine test within a couple weeks, if not days. If you're asking how long you stay high off one hit...depends on the weed and how often you smoke. But, usually not very long.
Manufacturers often design e-cigarettes to look like regular cigarettes, but they contain no tobacco and don't require a match -- or any flame at all. An e-cigarette is a battery-powered device that converts liquid nicotine into a mist, or vapor, that the user inhales. There's no fire, no ash and no smoky smell. E-cigarettes do not contain all of the harmful chemicals associated with smoking tobacco cigarettes, such as carbon monoxide and tar.
A vaporizer is a device which is used to free the active components of medicinal or recreational herbs so they can be inhaled for immediate effects. Vaporizing is a cleaner, healthier and more efficient alternative to smoking and incensing. vaporizer directs a flow of hot air through the plant material so the active components melt and create an aromatic vapor. Ideally this vapor doesn't contain any tars or unwanted gasses.