Help solve the question in a language C #?

[ahmadroos]

The program of conversion
1. Binary to decimal
2. Decimal to binary
3. Hex decimal to decimal
4. Decimal to hex decimal
5. Octal to decimal
6. Decimal to octal

Means at the user's request, for example, the introduction of No. 4
Convert from Decimal to hex decimal
Thus, the rest of the options, preferably without work ARRAYS

[ahmadroos]

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string ch;
            while (true)
            {
                Console.WriteLine("1 . convert from binary to decimal");
                Console.WriteLine("2 . convert from decimal to binary");
                Console.WriteLine("3 . convert from Hexdecimal to decimal");
                Console.WriteLine("4 . convert from decimal to hexdecimal");
                Console.WriteLine("5 . convert from octal to decimal");
                Console.WriteLine("6 . convert from decimal to octal");
                Console.WriteLine("7 . Exit");
                ch = Console.ReadLine();
                if (ch == "1")
                {
                    string binary;
                    Console.WriteLine("Enter the binary number");
                    binary = Console.ReadLine();
                    int power = 1;
                    int number = 0;
                    int counter = 0;
                    for (int i = binary.Length - 1; i <= 0; i--)
                    {
                        if (binary[i] == '1')
                            counter = number + power;
                        power = power * 2;

                    }

                }
                Console.WriteLine("the decimal number is :");



                if (ch == "2")
                {
                    int Number;
                    string binary = "";
                    Console.Write("Enter the decimal number ");
                    Number = Int32.Parse(Console.ReadLine());
                    while (Number > 0)
                    {
                        binary = Number % 2 + binary;
                        Number = Number / 2;

                    }

                    Console.WriteLine("the binary number is :",  binary , Number);

                }
                else if (ch == "3")
                {
                    break;
                }
            }
        }
    }
}

[DataMiser]

Is there a question in there somewhere?

[HanneSThEGreaT]

We usually do not do homework, but seeing that you have made a small effort, I'm posting.

Please, when asking a question, explain the nature of the problem and where the problem lies. Usually the debugger will let you know which line is giving a problem and it will provide an error message. Without this vital information, we cannot help properly.