使用此方法：

public static string getBetween(string strSource, string strStart, string strEnd)
{
    if (strSource.Contains(strStart) && strSource.Contains(strEnd))
    {
        int Start, End;
        Start = strSource.IndexOf(strStart, 0) + strStart.Length;
        End = strSource.IndexOf(strEnd, Start);
        return strSource.Substring(Start, End - Start);
    }

    return "";
}

如何使用它：

string source = "This is an example string and my data is here";
string data = getBetween(source, "my", "is");