Oops; you're right. One possible fix is for (size_t length = end - begin; length != 1; length = (length + 1) / 2) { size_t step = length / 2;

Oops; you're right. One possible fix is for (size_t length = end - begin; length != 1; length = (length + 1) / 2) { size_t step = length / 2; if (compare(begin[step], value)) begin += step; } return begin + compare(*begin, value); but it admittedly detracts from the simplicity of the former...