# Call and implement native UWP plug-ins

> Understand how to call and implement native plug-ins.

To call and implement native Universal Windows Platform (UWP) plug-ins, you need to know how to create native plug-ins for Unity. For more information about native plug-ins and their uses, refer to [Native plug-ins](/engine/6000.3/manual/scripting/compilation-and-code-reload/plug-ins/native.md).

IL2CPP scripting backend supports the P/Invoke mechanism for native plug-ins. This means that you can call into native plug-ins directly from your C# code. To do this, you specify the native function prototype and then call it.

The following examples show you how to implement a native plug-in and call it from a C# script.

1. Create a new .cpp file in your Unity project and insert the following native plug-in code:

   ```lang-cpp
       extern "C" __declspec(dllexport)
       int __stdcall CountLettersInString(wchar_t* str)
       {
           int length = 0;
           while (*str++ != nullptr)
               length++;
           return length;
       }
   ```

2. Create a new C# script and replace its contents with the following code:

   ```lang-cs
   [DllImport("MyPlugin.dll")]
       private static extern int CountLettersInString([MarshalAs(UnmanagedType.LPWStr)]string str);

       private void Start()
       {
           Debug.Log(CountLettersInString("Hello, native plug-in!"));
       }
   ```

3. Add the component to a GameObject in your scene and enter Play mode. The console will print 22.

   ```lang-cs
   using UnityEngine;
   public class ExamplePlugin : MonoBehaviour
   {
       [DllImport("MyPlugin.dll")]
       private static extern int CountLettersInString([MarshalAs(UnmanagedType.LPWStr)]string str);

       private void Start()
       {
           Debug.Log(CountLettersInString("Hello, native plug-in!"));
       }
   }
   ```

## Additional resources

* [Native plug-ins](/engine/6000.3/manual/scripting/compilation-and-code-reload/plug-ins/native.md)
* [Import and configure plug-ins](/engine/6000.3/manual/scripting/compilation-and-code-reload/plug-ins/plug-in-inspector.md)
* [Use P/invoke](/engine/6000.3/manual/platform-specific/windows-store/uwp-developing/uwp-il2cpp-scripting/uwp-il2cpp-plugins/uwp-pinvoke.md)