WM_GETTEXTLENGTH message

Determines the length, in characters, of the text associated with a window.

#define WM_GETTEXTLENGTH                0x000E

Parameters

wParam

This parameter is not used and must be zero.

lParam

This parameter is not used and must be zero.

Return value

Type: LRESULT

The return value is the length of the text in characters, not including the terminating null character.

Remarks

For an edit control, the text to be copied is the content of the edit control. For a combo box, the text is the content of the edit control (or static-text) portion of the combo box. For a button, the text is the button name. For other windows, the text is the window title. To determine the length of an item in a list box, an application can use the LB_GETTEXTLEN message.

When the WM_GETTEXTLENGTH message is sent, the DefWindowProc function returns the length, in characters, of the text. Under certain conditions, the DefWindowProc function returns a value that is larger than the actual length of the text. This occurs with certain mixtures of ANSI and Unicode, and is due to the system allowing for the possible existence of double-byte character set (DBCS) characters within the text. The return value, however, will always be at least as large as the actual length of the text; you can thus always use it to guide buffer allocation. This behavior can occur when an application uses both ANSI functions and common dialogs, which use Unicode.

To obtain the exact length of the text, use the WM_GETTEXT, LB_GETTEXT, or CB_GETLBTEXT messages, or the GetWindowText function.

Sending a WM_GETTEXTLENGTH message to a non-text static control, such as a static bitmap or static icon controlc, does not return a string value. Instead, it returns zero.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Header	Winuser.h (include Windows.h)

See also

Reference

DefWindowProc

GetWindowText

GetWindowTextLength

WM_GETTEXT

Conceptual

Windows

Other Resources

CB_GETLBTEXT

LB_GETTEXT

LB_GETTEXTLEN