Checking against off-by-one errors. When writing the selection sort algorithm of Section 14.1, a programmer must make the usual choices of < versus <=, a.length versus a.length - 1, and from versus from + 1. This is fertile ground for off-by-one errors. Conduct code walkthroughs of the algorithm with arrays of length 0, 1, 2, and 3 and check carefully that all index values are correct.