How do you handle the common off-by-one errors in binary search?

Off-by-one errors in binary search come from three sources: the loop condition, the mid calculation, and the pointer updates. Use "left less than or equal to right" when searching for an exact target, and "left less than right" when converging to a boundary. Calculate mid as left plus right minus left divided by two to avoid integer overflow. When eliminating the left half, set left to mid plus one. When eliminating the right half, set right to mid minus one for exact search or right to mid for boundary search.