Reverse an integer - do it yourself

reverseInteger_DoItYourself.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConvertIntToString
{
    /// <summary>
    /// July 4, 2017
    /// </summary>
    class Program
    {
        static void Main(string[] args)
        {
            var result = convertToString(-324);           
        }

        // Write a function that converts an int into its alpha-numeric equivalent represented 
        // as a null terminated string. The function should accept an int as input and return 
        // a string as output. For instance, calling the function with an int value of 324 would 
        // return a null terminated string containing "324". Ensure that your function checks for 
        // appropriate boundary conditions and edge cases. Assume you cannot use any standard 
        // libraries (for example, no itoa or sprintf).
       
        // Convert an int to alpha-numeric string 
        // let me think about module function:
        // 324 % 10 = 4, 
        // 324 / 10 = 32
        // go to next iteration        
        public static char[] convertToString(int n)
        {
            var reversed = new List<int>();  

            if (n == 0)
            {
                return new char[] { '0' };
            }
            
            bool isNonNegative = n >= 0;
            
            int unsignedInt = Math.Abs(n);

            while (unsignedInt > 0)
            {
                int remain      =  unsignedInt % 10;
                   unsignedInt  =  unsignedInt / 10;

                reversed.Add(remain);                                              
            }

            var length  = reversed.Count; 
            var newLength = isNonNegative? length: (length + 1);
            var result  = new char[newLength];

            int start = 0; 
            if (!isNonNegative)
            {
                result[0] = '-';
                start = 1; 
            }

            for (int i = length - 1; i >= 0; i-- )
            {
                result[start++] = (char)('0' + reversed[i]);
            }

            return result;
        }
    }
}