hello.cs

using System;
using System.Runtime.InteropServices;

class Newplus {
	[DllImport("./newplus/libnewplus.so")]
	public static extern long current_timestamp();
	[DllImport("./newplus/libnewplus.so")]
	public static extern int plusone(int x);

	public static void Main(string[] args) {
		if (args.Length < 1)
			throw new ArgumentException("First arg (0 - 2000000000) is required.");
		int iterations;
		if (int.TryParse(args[0], out iterations)) {
			if (iterations > 2000000000 || iterations < 0)
				throw new ArgumentException("Must be a positive number not exceeding 2 billion.");
		} else {
			throw new ArgumentException("Not a number.");
		}

		var start = current_timestamp();
		var x = 0;
		while (x < iterations) {
			x = plusone(x);
		}
		var end = current_timestamp();
		Console.WriteLine(end - start);
	}
}