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It depends if you are talking about boars specifically or hogs.
Boars can be very dangerous and agressive if wounded of feeling threatened. Do not cross them if you are unarmed.
Their size also varies a lot from places. Central europe has monsters as seen on the photo, called sus scroffa attila.
Also most boars can endure a lot of damage before dying. Americans hunt peaceful and static animals with a stealthy approach but in europe during driven hunts boars are running full of adrenaline chased by dogs and you really need an appropriate caliber and a good shot placement to make them drop on the spot. Otherwise they may run a long distance or charge you or the dogs.
Anyway don't underestimate them they also are very intelligent. Their meat is also very tasty.