C# substring完美截取HTML字符

注：此函数是在网上搜索得来，因此无法注明作者名，莫怪莫怪。嘿。
 /// <summary>
/// 按字节长度截取字符串(支持截取带HTML代码样式的字符串)
/// </summary>
/// <param name="content">将要截取的字符串参数</param>
/// <param name="length">截取的字节长度</param>
/// <param name="StripHTML">截取的结果是否为html代码</param>
/// <returns>截取的字符串</returns>
public static string GetContentSummary(string content, int length, bool StripHTML)
{
if (string.IsNullOrEmpty(content) || length == 0)
return "";
if (StripHTML)
{
System.Text.RegularExpressions.Regex re = new System.Text.RegularExpressions.Regex("<[^>]*>");
content = re.Replace(content, "");
content = content.Replace("　", "").Replace(" ", "").Replace(" ", "");
if (content.Length <= length)
return content;
else
return content.Substring(0, length) + "...";
}
else
{
if (content.Length <= length)
return content;
int pos = 0, npos = 0, size = 0;
bool firststop = false, notr = false, noli = false;
System.Text.StringBuilder sb = new System.Text.StringBuilder();
while (true)
{
if (pos >= content.Length)
break;
string cur = content.Substring(pos, 1);
if (cur == "<")
{
string next = content.Substring(pos + 1, 3).ToLower();
if (next.IndexOf("p") == 0 && next.IndexOf("pre") != 0)
{
npos = content.IndexOf(">", pos)