Object reference error on EnumChildWindow s

[prithvis.mohanty]

using System;
using System.Drawing;
using System.Componen tModel;
using System.Windows. Forms;
using System.Runtime. InteropServices ;
using System.Text;
using System.Collecti ons;
using System.Diagnost ics;

public delegate bool IECallBack(int hwnd, int lParam);
public delegate bool IEChildCallBack (int hWndParent,int lpEnumFunc,int
lParam);
namespace RunningInstance OfIE
{
/// <summary>
/// Summary description for IEHelper.
/// </summary>
public class IEHelper
{
[DllImport("user 32.Dll")]
public static extern int EnumWindows(IEC allBack x, int y);
[DllImport("User 32.Dll")]
public static extern void GetWindowText(i nt h, StringBuilder s, int
nMaxCount);
[DllImport("User 32.Dll")]
public static extern void GetClassName(in t h, StringBuilder s, int
nMaxCount);
[DllImport("User 32.Dll")]
public static extern IntPtr PostMessage(Int Ptr hWnd, int msg, int
wParam, int lParam);
[DllImport("User 32.dll")]
public static extern Boolean EnumChildWindow s(int
hWndParent,IECh ildCallBack lpEnumFunc,int lParam);
[DllImport("User 32.dll",CharSet =CharSet.Auto)]
private static extern int SendMessage(Int Ptr hWnd, int wMsg, IntPtr
wParam, string lParam);
static IntPtr windowHandle;
static StringBuilder sb, sbc;
static int i =0;
static ArrayList myAl;
private const int WM_SETTEXT = 0x000C;
private const int WM_KEYDOWN = 0x100;
public static string m_strToFind = "";
public static string m_strURL = "";
public IEHelper()
{
//
// TODO: Add constructor logic here
//
}
public static bool NavigateURL(str ing findStr, string urlStr)
{
m_strToFind = findStr.ToLower ();
m_strURL = urlStr.ToLower( );
myAl = new ArrayList();
IEChildCallBack chldCallBack = new
IEChildCallBack (EnumChildWindo wCallBack);
EnumWindows (new IECallBack(Enum WindowCallBack) , 0) ;
if(chldCallBack != null)
{
for(int i = 0 ; i < myAl.Count ; i++)
{
EnumChildWindow s((int)myAl[i] , chldCallBack, 0);
return true;

}
}
return true;
}
private static bool EnumChildWindow CallBack(int hwnd, int
lpEnumFunc, int lparam)
{
windowHandle = new IntPtr(hwnd);
sb = new StringBuilder(1 024);
sbc = new StringBuilder(2 56);
GetClassName(hw nd,sbc,sbc.Capa city);
GetWindowText(( int)windowHandl e, sb, sb.Capacity);
int x;
String xMsg = sb+" "+sbc+" "+windowHan dle;
if(sbc.ToString ().IndexOf("Edi t") >= 0 )
{
x = SendMessage(win dowHandle, WM_SETTEXT, new IntPtr(0),
m_strURL);
x = SendMessage(win dowHandle, WM_KEYDOWN, new IntPtr(0x0D), "");
}
return true;
}
private static bool EnumWindowCallB ack(int hwnd, int lParam)
{
windowHandle = (IntPtr)hwnd;
sb = new StringBuilder(1 024);
sbc = new StringBuilder(2 56);
GetClassName(hw nd,sbc,sbc.Capa city);
GetWindowText(( int)windowHandl e, sb, sb.Capacity);
String xMsg = sb+" "+sbc+" "+windowHan dle;
if( sbc.Length 0 )
{
if( sbc.ToString(). Equals("IEFrame ") &&
sb.ToString().T oLower().IndexO f(m_strToFind) >= 0 )
{
myAl.Add(hwnd);
i++;
}
}
return true;
}
}
}

I am trying to enumurate through all the open IE winodows to find out
a window with a specific title. once found brows a new url into it.
It works fine for one instance but after navigating I am getting an
object reference error on line

EnumChildWindow s((int)myAl[i] , chldCallBack, 0);

Can any one help on it ?

[Nicholas Paldino [.NET/C# MVP]]

Why not use automation to get all running instances of IE? The
following KB article shows how to connect to all running instances:

http://support.microsoft.com/kb/176792

It's in VB6, but you can easily adapt this code for .NET.

Hope this helps.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

<pr************ **@gmail.comwro te in message
news:11******** *************@r 35g2000prh.goog legroups.com...

using System;
using System.Drawing;
using System.Componen tModel;
using System.Windows. Forms;
using System.Runtime. InteropServices ;
using System.Text;
using System.Collecti ons;
using System.Diagnost ics;

public delegate bool IECallBack(int hwnd, int lParam);
public delegate bool IEChildCallBack (int hWndParent,int lpEnumFunc,int
lParam);
namespace RunningInstance OfIE
{
/// <summary>
/// Summary description for IEHelper.
/// </summary>
public class IEHelper
{
[DllImport("user 32.Dll")]
public static extern int EnumWindows(IEC allBack x, int y);
[DllImport("User 32.Dll")]
public static extern void GetWindowText(i nt h, StringBuilder s, int
nMaxCount);
[DllImport("User 32.Dll")]
public static extern void GetClassName(in t h, StringBuilder s, int
nMaxCount);
[DllImport("User 32.Dll")]
public static extern IntPtr PostMessage(Int Ptr hWnd, int msg, int
wParam, int lParam);
[DllImport("User 32.dll")]
public static extern Boolean EnumChildWindow s(int
hWndParent,IECh ildCallBack lpEnumFunc,int lParam);
[DllImport("User 32.dll",CharSet =CharSet.Auto)]
private static extern int SendMessage(Int Ptr hWnd, int wMsg, IntPtr
wParam, string lParam);
static IntPtr windowHandle;
static StringBuilder sb, sbc;
static int i =0;
static ArrayList myAl;
private const int WM_SETTEXT = 0x000C;
private const int WM_KEYDOWN = 0x100;
public static string m_strToFind = "";
public static string m_strURL = "";
public IEHelper()
{
//
// TODO: Add constructor logic here
//
}
public static bool NavigateURL(str ing findStr, string urlStr)
{
m_strToFind = findStr.ToLower ();
m_strURL = urlStr.ToLower( );
myAl = new ArrayList();
IEChildCallBack chldCallBack = new
IEChildCallBack (EnumChildWindo wCallBack);
EnumWindows (new IECallBack(Enum WindowCallBack) , 0) ;
if(chldCallBack != null)
{
for(int i = 0 ; i < myAl.Count ; i++)
{
EnumChildWindow s((int)myAl[i] , chldCallBack, 0);
return true;

}
}
return true;
}
private static bool EnumChildWindow CallBack(int hwnd, int
lpEnumFunc, int lparam)
{
windowHandle = new IntPtr(hwnd);
sb = new StringBuilder(1 024);
sbc = new StringBuilder(2 56);
GetClassName(hw nd,sbc,sbc.Capa city);
GetWindowText(( int)windowHandl e, sb, sb.Capacity);
int x;
String xMsg = sb+" "+sbc+" "+windowHan dle;
if(sbc.ToString ().IndexOf("Edi t") >= 0 )
{
x = SendMessage(win dowHandle, WM_SETTEXT, new IntPtr(0),
m_strURL);
x = SendMessage(win dowHandle, WM_KEYDOWN, new IntPtr(0x0D), "");
}
return true;
}
private static bool EnumWindowCallB ack(int hwnd, int lParam)
{
windowHandle = (IntPtr)hwnd;
sb = new StringBuilder(1 024);
sbc = new StringBuilder(2 56);
GetClassName(hw nd,sbc,sbc.Capa city);
GetWindowText(( int)windowHandl e, sb, sb.Capacity);
String xMsg = sb+" "+sbc+" "+windowHan dle;
if( sbc.Length 0 )
{
if( sbc.ToString(). Equals("IEFrame ") &&
sb.ToString().T oLower().IndexO f(m_strToFind) >= 0 )
{
myAl.Add(hwnd);
i++;
}
}
return true;
}
}
}

I am trying to enumurate through all the open IE winodows to find out
a window with a specific title. once found brows a new url into it.
It works fine for one instance but after navigating I am getting an
object reference error on line

EnumChildWindow s((int)myAl[i] , chldCallBack, 0);

Can any one help on it ?