README.md

083 - P/Invoke

P/Invoke is a way to allow unmanaged libraries from managed code. In the old days, it was a way to access Windows API that was not yet available in the .NET framework.

Since .NET became multi-platform, being present on Mac and Linux, P/Invoke has also been available on those platforms.

To import a native method that we would like to use, we need to create a static extern function and mark it with the DllImport attribute.

The DllImport attribute allows us to specify the native library from which the function should be loaded, as well as some extra parameters to cover more complex scenarios.

Docs 📑: https://learn.microsoft.com/en-us/dotnet/standard/native-interop/pinvoke

namespace PInvokeSamples;

public static class Program
{
    // Import the libc shared library and define the method
    // corresponding to the native function.
    [DllImport("libc.so.6")]
    private static extern int getpid();

    public static void Main(string[] args)
    {
        // Invoke the function and het the process ID
        int pid = getpid();
        Console.WriteLine(pid);
    }
}