求一正则表达式 文本框只接受半角英文和数字

Question

RT：求一正则表达式  文本框只接受半角英文和数字

Answer 1

数字是[0-9]+
半角英文  ？？  [a-zA-z]+那么全角英文呢？

Answer 2

Match   match   =   Regex.Match(strUserId,   @ "[0-9a-zA-Z]*${1,} ",   RegexOptions.IgnoreCase); 
                                if   (!match.ToString().Equals(strUserId)) 
                                { 
                                          MessageBox.Show( "ERROR ");; 
                                        return; 
                                }