How can I use C# to sort values numerically?

Question

I have a string that contains numbers separated by periods. When I sort it appears like this since it is a string: (ascii char order)

3.9.5.2.1.1
3.9.5.2.1.10
3.         


        

Answer 1

Split each string by '.', iterate through the components and compare them numerically.

This code also assumes that the number of components is signficant (a string '1.1.1' will be greater than '2.1'. This can be adjusted by altering the first if statement in the Compare method below.

    int Compare(string a, string b)
    {
        string[] aParts = a.Split('.');
        string[] bParts = b.Split('.');

        /// if A has more components than B, it must be larger.
        if (aParts.Length != bParts.Length)
            return (aParts.Length > bParts.Length) ? 1 : -1;

        int result = 0;
        /// iterate through each numerical component

        for (int i = 0; i < aParts.Length; i++)
            if ( (result = int.Parse(aParts[i]).CompareTo(int.Parse(bParts[i]))) !=0 )
                return result;

        /// all components are equal.
        return 0;
    }



    public string[] sort()
    {
        /// initialize test data
        string l = "3.9.5.2.1.1\n"
        + "3.9.5.2.1.10\n"
        + "3.9.5.2.1.11\n"
        + "3.9.5.2.1.12\n"
        + "3.9.5.2.1.2\n"
        + "3.9.5.2.1.3\n"
        + "3.9.5.2.1.4\n";

        /// split the large string into lines
        string[] arr = l.Split(new char[] { '\n' },StringSplitOptions.RemoveEmptyEntries);
        /// create a list from the array
        List strings = new List(arr);
        /// sort using our custom sort routine
        strings.Sort(Compare);
        /// concatenate the list back to an array.
        return strings.ToArray();
    }