Kill an Application with System Menu using C#

Figure 2. Displaying usage of Microsoft Spy++ Tool.

So lets examine the Win32 class, which has all the Platform Invoke declarations. This class will simply group all the functions we need for our application.

public class Win32
{
public const int WM_SYSCOMMAND = 0x0112;
public const int SC_CLOSE = 0xF060;
[DllImport("user32.dll")]
public static extern int FindWindow(
string lpClassName, // class name
string lpWindowName // window name
);
[DllImport("user32.dll")]
public static extern int SendMessage(
int hWnd, // handle to destination window
uint Msg, // message
int wParam, // first message parameter
int lParam // second message parameter
);
}

In C# the DllImport attribute is used to identify the name of the actual DLL that contains the exported functions. In order to apply the attribute the method must be defined as static and external.

We will be calling above class methods in button click event of Kill application. Following is the code snippet for it.

private void button1_Click(object sender, System.EventArgs e)
{
// Determine the handle to the Application window.
int iHandle=Win32.FindWindow(txtClsNm.Text ,txtWndNm.Text);
// Post a message to Application to end its existence.
int j=Win32.SendMessage(iHandle, Win32.WM_SYSCOMMAND, Win32.SC_CLOSE,0);
}



Figure 3. Kill application sending "Close Message" to Calculator application.

For further reading on Platform Invoke

• http://msdn.microsoft.com/library/default.asp?url=/library/en-us/csref/html
• /vcwlkplatforminvoketutorial.asp