C# __arglist 关键字

using System.Runtime.InteropServices;

namespace Alpha
{
    class Beta
    {
        [DllImport("msvcrt.dll")]
        static extern int scanf(string format, __arglist);
        [DllImport("msvcrt.dll")]
        static extern int printf(string format, __arglist);
        static void Main()
        {
            int a = ;
            int b = ;
            unsafe
            {
                scanf("%d%d", __arglist(&a, &b));
            }
            printf("%d + %d = %d\n", __arglist(a, b, a + b));
        }
    }
}