call-beep.cs

call-beep.cs

using System;
using System.Runtime.InteropServices;

class Prog
{
    static unsafe void Main()
    {
        var func = (delegate* unmanaged<int, int, int>)GetProcAddress(GetModuleHandle("kernel32.dll"), "Beep");
        int result = func(500, 500);
    }

    [DllImport("kernel32.dll"), SuppressGCTransition]
    static extern IntPtr GetProcAddress(IntPtr hModule, string entryPoint);

    [DllImport("kernel32.dll"), SuppressGCTransition]
    static extern IntPtr GetModuleHandle(string moduleName);
}