c#字符串类型转换

byte[] byteArray = System.Text.Encoding.Default.GetBytes(str);

string str = System.Text.Encoding.Default.GetString(byteArray);

byte[] byteArray = System.Text.Encoding.ASCII.GetBytes(str);

string str = System.Text.Encoding.ASCII.GetString(byteArray);

public static string (byte[] bytes)  
{
  string hexString = string.Empty;
  if(bytes != null)
  {
    StringBuilder strB = new StringBuilder();
    for(int i = 0; i < bytes.Length; i++)
    {
      strB.Append(bytes[i].ToString("x2"));
    }
    hexString = strB.ToString();
  }
  return hexString;
}

public static byte[] GetBytes(string hexString, out int discarded)
{
  discarded = 0;
  string newString = "";
  char c; //remove all none A-F, 0-9, characters
  for(int i = 0; i < hexString.Length; i++)
  {
    c = hexString[i];
    if(IsHexDig(c))
      new String += c;
    else
      discarded++;
  }   //if odd number of characters,discard last character
  if(newString.Length % 2 != 0)
  {
    discarded++;
    newString = newString.Substring(0, newString.Length - 1);
  }
  int byteLength = newString.Length / 2;
  byte[] bytes = new byte[byteLength];
  string hex;
  int j = 0;
  for(int i = 0; i < bytes.Length; i++)
  {
    hex = new String(new Char[]{newString[j], newString[j + 1]});
    bytes[i] = HexToByte(hex);
    j = j + 2;
  }
  return bytes;
}