public class SubstringInfo
{
    #region Constructors

    /// <summary>
    /// Initializes a new instance of the <see cref="SubstringInfo"/> class.
    /// </summary>
    /// <param name="original">The original String.</param>
    /// <param name="subString">The String to Extract</param>
    public SubstringInfo(String original, String subString)
    {
        OriginalString = original;
        StartIndex = original.IndexOf(subString);
        EndIndex = subString.Length;

        SubString = original.Substring(StartIndex, EndIndex);
    }

    #endregion

    #region Public Properties

    public Int32 SubStringLength
    {
        get { return SubString.Length; }
    }
    public Int32 OriginalStringLength
    {
        get { return OriginalString.Length; }
    }
    public Int32 StartIndex { get; private set; }
    public Int32 EndIndex { get; private set; }
    public String OriginalString { get; private set; }
    public String SubString { get; private set; }

    #endregion
}

static void Main(string[] args)
{
    String sub = "google";
    String original = "http://www.google.fr";

    SubstringInfo info = new SubstringInfo(original, sub);

    Console.WriteLine(info.StartIndex.ToString());
    Console.WriteLine(info.EndIndex.ToString());
    Console.WriteLine(info.OriginalString);
    Console.WriteLine(info.SubString);
}

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http://www.google.fr
google
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