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 digits as strings, and then compare the numeric values of the digits.