Copper snapped a three-day losing streak to end higher on Thursday, reacting to a weaker dollar and volatile crude oil prices, which eased back from an earlier spike above $100 a barrel. The most-active May COMEX copper contract gained 5.20 cents, or 1.2 percent, to settle at $4.3435 per lb. It hit an all-time high at $4.6575 on February 15.