C#将十进制转换为二进制

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

namespace Demo {
   class MyApplication {
      static void Main(string[] args) {

         int decVal;
         int val;
         string a = ;

         decVal = 34;
         Console.WriteLine(Decimal: {0}, decVal);

         while (decVal >= 1) {
            val = decVal / 2;
            a += (decVal % 2).ToString();
            decVal = val;
         }
         string binValue = ;

         for (int i = a.Length - 1; i >= 0; i--) {
            binValue = binValue + a[i];
         }

         Console.WriteLine(Binary: {0}, binValue);
         Console.Read();
      }
   }
}