GetWindowTextLengthW function (winuser.h)
Retrieves the length, in characters, of the specified window's title bar text (if the window has a title bar). If the specified window is a control, the function retrieves the length of the text within the control. However, GetWindowTextLength cannot retrieve the length of the text of an edit control in another application.
Syntax
int GetWindowTextLengthW(
[in] HWND hWnd
);
Parameters
[in] hWnd
Type: HWND
A handle to the window or control.
Return value
Type: int
If the function succeeds, the return value is the length, in characters, of the text. Under certain conditions, this value might be greater than the length of the text (see Remarks).
If the window has no text, the return value is zero.
Function failure is indicated by a return value of zero and a GetLastError result that is nonzero.
Note
This function does not clear the most recent error information. To determine success or failure, clear the most recent error information by calling SetLastError with 0, then call GetLastError.
Remarks
If the target window is owned by the current process, GetWindowTextLength causes a WM_GETTEXTLENGTH message to be sent to the specified window or control.
Under certain conditions, the GetWindowTextLength function may return 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. It can also occur when an application uses the ANSI version of GetWindowTextLength with a window whose window procedure is Unicode, or the Unicode version of GetWindowTextLength with a window whose window procedure is ANSI. For more information on ANSI and ANSI functions, see Conventions for Function Prototypes.
To obtain the exact length of the text, use the WM_GETTEXT, LB_GETTEXT, or CB_GETLBTEXT messages, or the GetWindowText function.
Note
The winuser.h header defines GetWindowTextLength as an alias which automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 2000 Professional [desktop apps only] |
| Minimum supported server | Windows 2000 Server [desktop apps only] |
| Target Platform | Windows |
| Header | winuser.h (include Windows.h) |
| Library | User32.lib |
| DLL | User32.dll |
| API set | ext-ms-win-ntuser-window-l1-1-1 (introduced in Windows 8.1) |
See also
Conceptual
Other Resources
Reference