An application sends an EM_LIMITTEXT message to limit the amount of text the user may enter into an edit control.
EM_LIMITTEXT
wParam = (WPARAM) cchMax; // text length, in characters
lParam = 0; // not used; must be zero
Parameters
cchMax
Value of wParam. Specifies the maximum number of characters the user can enter. If this parameter is zero, the text length is set to 0x7FFFFFFE characters for single-line edit controls or 0xFFFFFFFF for multiline edit controls.
Return Values
This message does not return a value.
Remarks
The EM_LIMITTEXT message limits only the text the user can enter. It has no effect on any text already in the edit control when the message is sent, nor does it affect the length of the text copied to the edit control by the WM_SETTEXT message. If an application uses the WM_SETTEXT message to place more text into an edit control than is specified in the EM_LIMITTEXT message, the user can edit the entire contents of the edit control.
The default limit to the amount of text a user can enter in an edit control is 30,000 characters.
In a rich edit control, use the message EM_EXLIMITTEXT for text length values greater than 64K.
See Also