using System;

using System.Reflection;

​

public class Program

{

    public static void Main()

    {

        var targetMethod = typeof(Program).GetMethod("DoSomething", BindingFlags.NonPublic | BindingFlags.Static);

        var parameters = targetMethod.GetParameters();

        foreach (var parameter in parameters) {

            Console.WriteLine(parameter.ParameterType.GetElementType());

        }

    }

    private static void DoSomething(int[] numbers) {

    }

}