Conversione Esadecimale

public string ConvertToHex(int num)
{
  char[] buffer= new char[Convert.ToString(num).Lenght];
  char[] car = new char[]{'A','B','C','D','E','F'};
  for(int val1=num, int i=0; val1!=0; val1/=16, i++)
       buffer[i] = (num%16<10) ? Convert.ToChar(val2) : car[val2-10];
  string result = "";
  for (int j=buffer.Lenght-1; j>=0; j--) result+=Convert.ToString(buffer[j]); 
  return result;
}