.net正则匹配

char[] weixin = txtweixinhao.Text.Trim().ToCharArray();
for (int i = 0; i < weixin.Length; i++)
if (weixin[i] >= 0x4e00 && weixin[i] <= 0x9fbb)
{
functions.ComShow(this.Page, "微信号不能包含中文");
this.txtweixinhao.Focus();
return;
}