An application sends a WM_SETTEXT message to set the text of a window. 
SyntaxTo send this message, call the SendMessage function as follows. 
    lResult = SendMessage(      // returns LRESULT in lResult     
       (HWND) hWndControl,      // handle to destination control     
       (UINT) WM_SETTEXT,       // message ID     
       (WPARAM) wParam,         // = (WPARAM) () wParam;    
       (LPARAM) lParam          // = (LPARAM) () lParam; 
    );   
Parameters
- wParam This parameter is not used. 
 - lParam Pointer to a null-terminated string that is the window text. 
 
Return Value
The return value is TRUE if the text is set. It is FALSE (for an edit control), LB_ERRSPACE (for a list box), or CB_ERRSPACE (for a combo box) if insufficient space is available to set the text in the edit control. It is CB_ERR if this message is sent to a combo box without an edit control. 
Remarks
The DefWindowProc function sets and displays the window text. For an edit control, the text is the contents of the edit control. For a combo box, the text is the contents of the edit-control portion of the combo box. For a button, the text is the button name. For other windows, the text is the window title. 
This message does not change the current selection in the list box of a combo box. An application should use the CB_SELECTSTRING message to select the item in a list box that matches the text in the edit control. 
Message Information
-  Header Declared in Winuser.h, include Windows.h 
 -  Minimum operating systems Windows 95, Windows NT 3.1