OK will do that .

Many Thanks
Sid

Looks good, except I strongly suggest that you send a LB_GETTEXTLEN before each LB_GETTEXT to ensure that the text is not too long. It seems unnecessary but it is better to be sure.

I have directly replaced hWndListBox = (IntPtr)ListBoxId; I have ListBoxId from  SPY++

This works for me to extract data from listbox. Sam thanks for all the information shared.

Probably the reason for the different results using GetDlgItem and FindWindowEx is that the class name is used more than once. If you call FindWindowEx again using the first button's handle as hwndChildAfter then you will likely get another button.

I am sorry that I was not clear. I meant to use FindWindowEx to find Window F then use GetDlgItem to get the ListBox.

FindWindowEx however does not work the way I was thinking it does. The reason why is quite technical; it involves the difference between owned windows and child windows. So it will not work to specify a window handle with FindWindowEx, which means that you will search all windows in the system for a specified class name. That might work. Use null for hwndParent, Window F's class name for lpszClass and null for hwndChildAfter and lpszWindow. If you get a window using that then I suggest making a second call to FindWindowEx using that handle in hwndChildAfter and Window F's class name for lpszClass. If you get a window from the second call then that means there are more than one windows with that class name and that is a probable problem. If you get one and only one window then you can use GetDlgItem to get the ListBox.

For a known handle if I am doing 

IntPtr hWndButton = GetDlgItem(handle, ButtonId); //returns 131740

whereas if I do

IntPtr hWndButton = FindWindowEx(handle, IntPtr.Zero, "WindowsForms10.BUTTON.app.0.378734a", null); // returns 131700


for the same button  using class name search it gives a different result??

If the first solution works it would  be great , I checked that my listbox as a unique classname
"WindowsForms10.LISTBOX.app.0.378734a"

So I am doing this

 IntPtr hWndListBox = FindWindowEx(handle, IntPtr.Zero, "WindowsForms10.LISTBOX.app.0.378734a",null );

but still my hWndListBox is null.

Regards
Sid

I might not understand the situation. There are probably at least two possible solutions.

If you are lucky then Window F has a unique class name. In Spy++ the properties of a window has a Class tab. At the top of the Class tab is a class name. If that class name is unique then you can use that. You can use the FindWindowEx function with the window handle for Window A and the class name. You can use NULL for hwndChildAfter and lpszWindow.

If it is not possible to do that then hopefully you can walk the window hierarchy. Look at the GetWindow function. You can use it to do various things to find windows depending on the relationship of the windows. I assume that Window B is the first child of Window A, so you get the child of Window A. Then get the first window in the Z-order (GW_HWNDNEXT) and that should be Window C. Then get the child of Window C. If it were me I would add logic that does something to ensure it is working as expected; something such as checking the window titles (either the entire title or a portion of it) (using a WM_GETTEXT message I think) but that depends on your application. Use whatever works for your application to check each window to ensure it is the correct window so if the application changes then your application will fail gracefully.

There might be other ways to do it but it depends on your application. You can look at the Windows API functions in case something else will help.

Hi Sam Can you help me with this, I have a window  heirarchy has  shown below

Window 0001027C "A"
        Window 0001028E "B"
        Window 000102B4 "C"
                 Window 00170108 "D"
                        Window 00C00FE "E"
                                Window 001003A6 "F"


F is my target Listbox I need  handle for F and  A is the process main window with the below code from your earlier article I get handle  for the mainwindow A. 

 IntPtr hWndListBox = GetDlgItem(handle, ListBoxId);

How to do get handle for my listbox which is in child window. The above code works for the immediate child widgets.

The link in my previous post for the macros is incorrect but since the post has source code in it I do not want to edit the post. The correct link is List Box Macros.

I will try the C# solution. Many thanks for all the information. It helps.

So you will want to send a LB_GETCOUNT message (ListBox_GetCount macro) then for each item send a LB_GETTEXTLEN (ListBox_GetTextLen) and LB_GETTEXT (ListBox_GetText). You can do the equivalent in C# using SendMessage. I hope my article about clicking a button in another application helps you to figure out how to do that.

It is easier in C++ if you are more familiar with it since the Windows API is designed to work with C++. See List Box Controls for the documentation of List Box Controls. For C++ there is a set of macros that make it especially easy to send API messages. See List Box for the List Box macros.

The following is a C++ console application that gets the items of a ComboBox. I used a ComboBox just because it is easier for me to find one for testing with. It is easy to do the equivalent for List Boxes.

int n = ComboBox_GetCount(hWnd);
std::wcout << n << L'\n';
_TCHAR Buffer[100];
int length;
for (int i=0; ilength = ComboBox_GetLBTextLen(hWnd, i);
if (length < 99) {
ComboBox_GetLBText(hWnd, i, Buffer);
std::wcout << Buffer << L'\n';
}
else
std::wcout << "Item " << i << " is too big\n";
}

The stdafx.h file for that is:

#pragma once

#include "targetver.h"

#include
#include
#include
#include

#include
#include