转(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;
        }

private static byte[] HexToByte(string hexString)
{
byte[] returnBytes = new byte[hexString.Length / 2];
for (int i = 0; i < returnBytes.Length; i++)
returnBytes[i] = Convert.ToByte(hexString.Substring(i * 2, 2), 16);
return returnBytes;
}
 private int HexToByte(string hex)
        {
           int result;
            result = 0;
       
            switch (hex[0])
            {
                case '0': result = 0x00; break;
                case '1': result = 0x10; break;
                case '2': result = 0x20; break;
                case '3': result = 0x30; break;
                case '4': result = 0x40; break;
                case '5': result = 0x50; break;
                case '6': result = 0x60; break;
                case '7': result = 0x70; break;
                case '8': result = 0x80; break;
                case '9': result = 0x90; break;
                case 'a':
                case 'A': result = 0xa0; break;
                case 'b':
                case 'B': result = 0xb0; break;
                case 'c':
                case 'C': result = 0xc0; break;
                case 'd':
                case 'D': result = 0xd0; break;
                case 'e':
                case 'E': result = 0xe0; break;
                case 'f':
                case 'F': result = 0xf0; break;

            }
            switch (hex[1])
            {
                case '0': result +=0x00; break;
                case '1': result += 0x01; break;
                case '2': result += 0x02; break;
                case '3': result += 0x03; break;
                case '4': result += 0x04; break;
                case '5': result += 0x05; break;
                case '6': result += 0x06; break;
                case '7': result += 0x07; break;
                case '8': result += 0x08; break;
                case '9': result += 0x09; break;
                case 'a':
                case 'A': result += 0x0a; break;
                case 'b':
                case 'B': result += 0x0b; break;
                case 'c':
                case 'C': result += 0x0c; break;
                case 'd':
                case 'D': result += 0x0d; break;
                case 'e':
                case 'E': result += 0x0e; break;
                case 'f':
                case 'F': result += 0x0f; break;

            }

            return result;
        }

来源：https://www.cnblogs.com/seacode/archive/2009/08/31/1557501.html