All Possible Combinations of a list of Values

AllCombinations.cs

namespace Combinations
{
	public class Combinations
	{
		public static void Main(string[] args)
		{
		    GetCombination(new List<int> { 1, 2, 3 });
		}

		public static void GetCombination(List<int> list)
		{
		    double count = Math.Pow(2, list.Count);
		    for (int i = 1; i <= count - 1; i++)
		    {
		        string str = Convert.ToString(i, 2).PadLeft(list.Count, '0');
		        for (int j = 0; j < str.Length; j++)
		        {
		            if (str[j] == '1')
		            {
		                Console.Write(list[j]);
		            }
		        }
		        Console.WriteLine();
		    }
		}
	}
}

PROBLEM STATEMENT

I have a list of integers in my C# program. However, I know the number of items I have in my list only at run-time.

Let us say, for the sake of simplicity, my list is {1, 2, 3}
Now I need to generate all possible combinations as follows.

{1, 2, 3} {1, 2} {1, 3} {2, 3} {1} {2} {3}