string和byte[]的转换 (C#)

string类型转成byte[]：

byte[] byteArray = System.Text.Encoding.Default.GetBytes ( str );
反过来，byte[]转成string：

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

其它编码方式的，如System.Text.UTF8Encoding，System.Text.UnicodeEncoding class等；例如：

string类型转成ASCII byte[]：（"01" 转成 byte[] = new byte[]{ 0x30, 0x31}）

byte[] byteArray = System.Text.Encoding.ASCII.GetBytes ( str );
ASCII byte[] 转成string：（byte[] = new byte[]{ 0x30, 0x31} 转成 "01"）

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

有时候还有这样一些需求：

byte[] 转成原16进制格式的string，例如0xae00cf, 转换成 "ae00cf"；new byte[]{ 0x30, 0x31}转成"3031":

public static string ToHexString ( byte[] bytes ) // 0xae00cf => "AE00CF "
{
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;
}

反过来，16进制格式的string 转成byte[]，例如, "ae00cf"转换成0xae00cf，长度缩减一半；"3031" 转成new byte[]{ 0x30, 0x31}:

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 (IsHexDigit(c))
newString += 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;
}