asp.net c#与vb.net 只能输入英文和数字函数

本文章也是针对于asp教程.net来做的，就是关于asp.net教程 c#与vb.net 只能输入英文和数字函数，第一款是c#限制只能输入数字与英文，后一示是vb.net做的，原理都一个个字符然后判断他的内码值如下实例。

private void textbox1_textchanged(object sender, eventargs e)
        {
            char[] clist = textbox1.text.tochararray();
            string newstr = "";
            for (int i = 0; i < clist.length; i++)
            {
                int ascii = (int)clist[i];
                if (ascii > 127)
                {
                    clist[i] = '';
                }
                newstr += clist[i].tostring();
            }

            textbox1.text = newstr;
        }

vb.net

function valitext(keyin as integer, validatestring as string, editable as boolean) as integer
          dim validatelist as string
          dim keyout as integer

          if editable = true then
                  validatelist = ucase(validatestring) & chr(8)
          else
                  validatelist = ucase(validatestring)
          end if

          if instr(1, validatelist, ucase(chr(keyin)), 1) > 0 then
                  keyout = keyin
          else
                  keyout = 0
          end if
          valitext = keyout
end function

调用方法

private sub txtmoney_keypress(keyascii as integer)
          keyascii = valitext(keyascii, "0123456789.", true)
end sub

private sub txtid_keypress(keyascii as integer)
          keyascii = valitext(keyascii, "0123456789-abcdefghijklmnopqrstuvwxyz", true)
end sub

补充：asp.net教程,C语言