How do I call a method in the main in C#?

Quote:

Thank you, I thought of that, but I was actually wondering what to code to put there to call it.

As Richard has said, the static Main method is called automatically for you - that's why an assembly can only ever have one static method called Main, regardless of how many classes it contains.

Once you have that, you can call your method(s) as necessary:

using System;
using System.Linq;

namespace ConsoleApp1
    {
        public class Program
        {
            public int[] SwitchLights(int[] a)
            {
                var count = a.Count(t => t == 1);
                for (int i = 0; i < a.Length; i++)
                {
                    var current = count;
                    if (a[i] == 1) count--;
                    if (current % 2 == 1) a[i] = a[i] == 1 ? 0 : 1;
                }
                return a;
            }
            static void Main(string[] args)
            {
                int[] myArray = new int[] {1, 2, 3, 4, 5, 6, 7, 8, 9};
				Program myProg = new Program();
                myArray = myProg.SwitchLights(myArray);
            }
        }
    }

Once the static Main method runs, it will terminate immediately (the window will close) ... unless you use ReadKey, or ReadLine to cause the thread to stop.

A common technique is to run a 'while loop that keeps the process/window going until some exit condition is met.

You can see some techniques for Console programming here: [^]