The input length of textbox is limited. The length of the input is two Chinese characters, one English byte.

 

Textbox. maxlength can limit the length of the input content. But how can we limit the length of an ANSI string to be more precise?

In ANSI encoding, Chinese occupies 2 bytes and English 1 byte. textbox. maxlength cannot be limited to ANSI strings mixed with Chinese and English.

 

Consider the following method to limit the input length:

1. maxlength

2. Handling in keypress events

3. Process in textchanged

Dim oldtxt = ""
Private sub txtsingletxt_textchanged (sender as system. Object, e as system. eventargs) handles txtsingletxt. textchanged
Dim c = SMS. Global. maxlen-SMS. Global. txtlen (txtsingletxt. Text)
Lbcount3.text = C
If (C <0) then
Txtsingletxt. Text = oldtxt
Else
Oldtxt = txtsingletxt. Text
End if
End sub

 

Private sub tbparentsmsg_keypress (sender as system. Object, e as system. Windows. Forms. keypresseventargs) handles tbparentsmsg. keypress
Dim c = SMS. Global. maxlen-SMS. Global. txtlen (tbparentsmsg. Text)
Lbcount3.text = C
If (C <= 0 and (vbback <> E. keychar) then
E. Handled = true
End if
End sub