public List<string> BetweenArr(string str, string leftstr, string rightstr)
{
    List<string> list = new List<string>();
    int leftIndex = str.IndexOf(leftstr);//左文本起始位置
    int leftlength = leftstr.Length;//左文本长度
    int rightIndex = 0;
    string temp = "";
    while (leftIndex != -1)
    {
        rightIndex = str.IndexOf(rightstr, leftIndex + leftlength);
        if (rightIndex == -1)
        {
            break;
        }
        temp = str.Substring(leftIndex + leftlength, rightIndex - leftIndex - leftlength);
        list.Add(temp);
        leftIndex = str.IndexOf(leftstr, rightIndex + 1);
    }
    return list;
}