<div>
<a href="http://www.codeproject.com/KB/cs/singleinstance.aspx" rel="ugc">http://www.codeproject.com<wbr />/KB/cs/sin<wbr />gleinstanc<wbr />e.aspx</a><br />
<a href="http://www.codeproject.com/KB/dotnet/csharponeinst.aspx" rel="ugc">http://www.codeproject.com<wbr />/KB/dotnet<wbr />/csharpone<wbr />inst.aspx</a><br />
&nbsp;<a href="http://iridescence.no/post/CreatingaSingleInstanceApplicationinC.aspx" rel="ugc">http://iridescence.no/post<wbr />/Creatinga<wbr />SingleInst<wbr />anceApplic<wbr />ationinC.a<wbr />spx</a><br />
&nbsp;<br />

</div>


http://www.codeproject.com/KB/cs/singleinstance.aspx [http://www.codeproject.com/KB/cs/singleinstance.aspx]
http://www.codeproject.com/KB/dotnet/csharponeinst.aspx [http://www.codeproject.com/KB/dotnet/csharponeinst.aspx]
 http://iridescence.no/post/CreatingaSingleInstanceApplicationinC.aspx [http://iridescence.no/post/CreatingaSingleInstanceApplicationinC.aspx]
 


<div>
 Maybe the simplest way:<br />
using System.Diagnostics;<br />
Process[] processes = Process.GetProcessesByName<wbr />(&quot;myapp&quot;);<wbr /> <br />
foreach (Process p in processes) <br />
{ <br />
&nbsp; &nbsp; IntPtr pFoundWindow = p.MainWindowHandle; <br />
&nbsp; &nbsp; // Do something with the handle... <br />
&nbsp; &nbsp; p.CloseMainWindow();<br />
} <br />
<a href="http://msdn.microsoft.com/en-us/library/system.diagnostics.process.getprocessesbyname.aspx" rel="ugc">http://msdn.microsoft.com/<wbr />en-us/libr<wbr />ary/system<wbr />.diagnosti<wbr />cs.process<wbr />.getproces<wbr />sesbyname.<wbr />aspx</a><br />

</div>


Maybe the simplest way:
using System.Diagnostics;
Process[] processes = Process.GetProcessesByName("myapp");
foreach (Process p in processes)
{
    IntPtr pFoundWindow = p.MainWindowHandle;
    // Do something with the handle...
    p.CloseMainWindow();
}
http://msdn.microsoft.com/en-us/library/system.diagnostics.process.getprocessesbyname.aspx [http://msdn.microsoft.com/en-us/library/system.diagnostics.process.getprocessesbyname.aspx]


<div>
Ooops... forgot to say, put that code into Program.cs.
</div>


Ooops... forgot to say, put that code into Program.cs.

<div>
Axshun I used your code and it seems to work except for my Form1 is hiden and when I run the code it becomes visible.<br />
<br />
How can I solve this?<br />
<br />
Thanks
</div>


Axshun I used your code and it seems to work except for my Form1 is hiden and when I run the code it becomes visible.

How can I solve this?

Thanks

<div>
<div class="content wysiwyg-content">
I have a C# app that should not have multiple instances running.<br />
<br />
And if there is another instance running then kill the old process and run the one user is currently opening.<br />
<br />
Thanks
</div>
</div>


I have a C# app that should not have multiple instances running.

And if there is another instance running then kill the old process and run the one user is currently opening.

Thanks

One App Running at a time

C# is an object-oriented programming language created in conjunction with Microsoft’s .NET framework. Compilation is usually done into the Microsoft Intermediate Language (MSIL), which is then JIT-compiled to native code (and cached) during execution in the Common Language Runtime (CLR).

Microsoft Visual C++ (often abbreviated as MSVC or VC++) is an integrated development environment (IDE) product from Microsoft for the C, C++, and C++/CLI programming languages. It features tools for developing and debugging C++ code, especially code written for the Microsoft Windows API, the DirectX API, and the Microsoft .NET Framework. Many applications require redistributable Visual C++ packages to function correctly and are often installed independently of applications, allowing multiple applications to make use of the package while only having to install it once