TrimNumbers.cs

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

namespace Pangea
{
    class Program
    {
        public static string TrimNumbers(string s, int maxCharCount)
        {
            string output = "";

            if (s.Length == maxCharCount)
                return s;
            
            for(int i = 0; i < maxCharCount; i++)
            {
                if(i == maxCharCount - 1)
                {
                    // Check for last character being a comma
                    if(s[i] == ',')
                    {
                        break;
                    }
                    
                    // Check to see if this is a floating point
                    if(i + 1 < s.Length && s[i + 1] == '.')
                    {
                        int position = i;
                        while(s[--position] != ',' && position >= 0) {
                            output = s.Remove(i - 1);
                        }

                        // Remove last comma
                        // Handle edge cases
                        if(position >= 0)
                            output = s.Remove(position);

                        break;
                    }
                }

                output += s[i];
            }
            return output;
        }

        static void Main(string[] args)
        {
            string input = "4.5,6.76666666666666";
            string expectedOutput = "4.5";

            string decimalOutput = TrimNumbers(input, 5);

            if (decimalOutput != expectedOutput)
            {
                Console.WriteLine("Error: Invalid output, got " + "\"" + 
                    decimalOutput + "\"" + ", expecting " + "\"" + expectedOutput + "\"");
            }

            Console.WriteLine(decimalOutput);

            input = "1,2,3";
            expectedOutput = "1,2,3";

            string wholeNumberOutput = TrimNumbers(input, 5);

            if (wholeNumberOutput != expectedOutput)
            {
                Console.WriteLine("Error: Invalid output, got " + "\"" +
                    wholeNumberOutput + "\"" + ", expecting " + "\"" + expectedOutput + "\"");
            }

            Console.WriteLine(wholeNumberOutput);

            Console.Read();
        }
    }
}