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GetWindowText function

Copies the text of the specified window's title bar (if it has one) into a buffer. If the specified window is a control, the text of the control is copied. However, GetWindowText cannot retrieve the text of a control in another application.

Syntax

Copy 
int WINAPI GetWindowText(
  __in   HWND hWnd,
  __out  LPTSTR lpString,
  __in   int nMaxCount
);

Parameters

hWnd [in]

Type: HWND

A handle to the window or control containing the text.

lpString [out]

Type: LPTSTR

The buffer that will receive the text. If the string is as long or longer than the buffer, the string is truncated and terminated with a null character.

nMaxCount [in]

Type: int

The maximum number of characters to copy to the buffer, including the null character. If the text exceeds this limit, it is truncated.

Return value

Type: int

If the function succeeds, the return value is the length, in characters, of the copied string, not including the terminating null character. If the window has no title bar or text, if the title bar is empty, or if the window or control handle is invalid, the return value is zero. To get extended error information, call GetLastError.

This function cannot retrieve the text of an edit control in another application.

Remarks

If the target window is owned by the current process, GetWindowText causes a WM_GETTEXT message to be sent to the specified window or control. If the target window is owned by another process and has a caption, GetWindowText retrieves the window caption text. If the window does not have a caption, the return value is a null string. This behavior is by design. It allows applications to call GetWindowText without becoming unresponsive if the process that owns the target window is not responding. However, if the target window is not responding and it belongs to the calling application, GetWindowText will cause the calling application to become unresponsive.

To retrieve the text of a control in another process, send a WM_GETTEXT message directly instead of calling GetWindowText.

Examples

For an example, see Sending a Message.

Requirements

Minimum supported client

Windows 2000 Professional

Minimum supported server

Windows 2000 Server

Header
Winuser.h (include Windows.h)

Library
User32.lib

DLL
User32.dll

Unicode and ANSI names

GetWindowTextW (Unicode) and GetWindowTextA (ANSI)

See also

Reference
GetWindowTextLength
SetWindowText
WM_GETTEXT
Conceptual
Windows

 

 

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Build date: 9/11/2011

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Community Content Add
Annotations FAQ
Ex: Getting parent Form's caption
Private Declare Function SetParent Lib "user32.dll" (ByVal hWndChild As Long, ByVal hWndNewParent As Long) As Long
Private Declare Function GetParent Lib "user32" (ByVal hWnd As Long) As Long
Private Declare Function GetWindowText Lib "user32" Alias "GetWindowTextA" (ByVal hWnd As Long, ByVal lpString As String, ByVal cch As Long) As Long

Public Function GetParentFormCaption(ByVal lngHwnd As Long) As String
  Dim strBuff As String * 255
  Dim lngOldHwnd As Long, lngResult As Long
 
  lngOldHwnd = GetParent(lngHwnd)
  lngResult = GetWindowText(lngOldHwnd, strBuff, Len(strBuff))
 
  GetParentFormCaption = Trim(strBuff)
End Function

NOTE: The "GetParentFormCaption()" will get the parent-form's, only if the calling form is set as child at runtime [using 'SetParent()'].
History
The secret life of GetWindowText
The old New Thing:
http://blogs.msdn.com/oldnewthing/archive/2003/08/21/54675.aspx
History
C# syntax 
[DllImport("user32", CharSet=CharSet.Auto, SetLastError=true)]
internal static extern int GetWindowText(IntPtr hWnd, [Out, MarshalAs(UnmanagedType.LPTStr)] StringBuilder lpString, int nMaxCount);
History
vb.net syntax 
<DllImport("user32", CharSet:=CharSet.Auto, SetLastError:=True)> _
Public Shared Function GetWindowText(ByVal hWnd As IntPtr, <Out, MarshalAs(UnmanagedType.LPTStr)> ByVal lpString As StringBuilder, ByVal nMaxCount As Integer) As Integer
End Function
History
Possible VB9 declaration 
Friend Declare Auto Function GetWindowText Lib "user32.dll" (ByVal hwnd As Int32, <Out()> ByVal lpString As System.Text.StringBuilder, ByVal cch As Int32) As Int32

Example:

                Dim len As Integer = API.GetWindowTextLength(hWnd)
                If len > 0 Then
                    Dim b As New System.Text.StringBuilder(ChrW(0), len + 1)
                    Dim ret = API.GetWindowText(hWnd, b, b.Capacity)
                    If ret <> 0 Then
                        Return b.ToString
                    Else
                        Throw New API.Win32APIException
                    End If
                Else
                    Dim ex As New API.Win32APIException
                    If ex.NativeErrorCode <> 0 Then
                        Throw New API.Win32APIException
                    Else
                        Return ""
                    End If
                End If
History