Bentley [Ben00, Chap. 4] provides the following informal description of binary search:

We are to determine whether the sorted array X[1..N] contains the element T. . . . Binary search solves the problem by keeping track of a range within the array in which T must be if it is anywhere in the array. Initially, the range is the entire array. The range is shrunk by comparing its middle element to T and discarding half the range. The process continues until T is discovered in the array or until the range in which it must lie is known to be empty.

Write code for binary search in your favorite imperative programming language. What loop construct(s) did you find to be most useful? NB: when he asked more than a hundred professional programmers to solve this problem, Bentley found that only about 10% got it right the first time, without testing.