It is common for people to name directories as dir1, dir2, and so on. when there are ten or more directories, the operating system displays them in dictionary order, as dir1, dir10, dir11, dir12, dir2, dir3, and so on. that is irritating, and it is easy to fix. provide a comparator that compares strings that end in digit sequences in a way that makes sense to a human. first compare the part before the digit as strings, and then compare the numeric values of the digits.