如何将字节数组转换为十六进制字符串，反之亦然？
当前回答
支持最短路径和.net核心：
public static string BytesToString(byte[] ba) =>
ba.Aggregate(new StringBuilder(32), (sb, b) => sb.Append(b.ToString("X2"))).ToString();
其他回答
我将参加这个比特拨弄比赛，因为我有一个同样使用比特拨弄来解码十六进制的答案。请注意，使用字符数组可能会更快，因为调用StringBuilder方法也需要时间。
public static String ToHex (byte[] data)
{
int dataLength = data.Length;
// pre-create the stringbuilder using the length of the data * 2, precisely enough
StringBuilder sb = new StringBuilder (dataLength * 2);
for (int i = 0; i < dataLength; i++) {
int b = data [i];
// check using calculation over bits to see if first tuple is a letter
// isLetter is zero if it is a digit, 1 if it is a letter
int isLetter = (b >> 7) & ((b >> 6) | (b >> 5)) & 1;
// calculate the code using a multiplication to make up the difference between
// a digit character and an alphanumerical character
int code = '0' + ((b >> 4) & 0xF) + isLetter * ('A' - '9' - 1);
// now append the result, after casting the code point to a character
sb.Append ((Char)code);
// do the same with the lower (less significant) tuple
isLetter = (b >> 3) & ((b >> 2) | (b >> 1)) & 1;
code = '0' + (b & 0xF) + isLetter * ('A' - '9' - 1);
sb.Append ((Char)code);
}
return sb.ToString ();
}
public static byte[] FromHex (String hex)
{
// pre-create the array
int resultLength = hex.Length / 2;
byte[] result = new byte[resultLength];
// set validity = 0 (0 = valid, anything else is not valid)
int validity = 0;
int c, isLetter, value, validDigitStruct, validDigit, validLetterStruct, validLetter;
for (int i = 0, hexOffset = 0; i < resultLength; i++, hexOffset += 2) {
c = hex [hexOffset];
// check using calculation over bits to see if first char is a letter
// isLetter is zero if it is a digit, 1 if it is a letter (upper & lowercase)
isLetter = (c >> 6) & 1;
// calculate the tuple value using a multiplication to make up the difference between
// a digit character and an alphanumerical character
// minus 1 for the fact that the letters are not zero based
value = ((c & 0xF) + isLetter * (-1 + 10)) << 4;
// check validity of all the other bits
validity |= c >> 7; // changed to >>, maybe not OK, use UInt?
validDigitStruct = (c & 0x30) ^ 0x30;
validDigit = ((c & 0x8) >> 3) * (c & 0x6);
validity |= (isLetter ^ 1) * (validDigitStruct | validDigit);
validLetterStruct = c & 0x18;
validLetter = (((c - 1) & 0x4) >> 2) * ((c - 1) & 0x2);
validity |= isLetter * (validLetterStruct | validLetter);
// do the same with the lower (less significant) tuple
c = hex [hexOffset + 1];
isLetter = (c >> 6) & 1;
value ^= (c & 0xF) + isLetter * (-1 + 10);
result [i] = (byte)value;
// check validity of all the other bits
validity |= c >> 7; // changed to >>, maybe not OK, use UInt?
validDigitStruct = (c & 0x30) ^ 0x30;
validDigit = ((c & 0x8) >> 3) * (c & 0x6);
validity |= (isLetter ^ 1) * (validDigitStruct | validDigit);
validLetterStruct = c & 0x18;
validLetter = (((c - 1) & 0x4) >> 2) * ((c - 1) & 0x2);
validity |= isLetter * (validLetterStruct | validLetter);
}
if (validity != 0) {
throw new ArgumentException ("Hexadecimal encoding incorrect for input " + hex);
}
return result;
}
从Java代码转换而来。
可以使用从.NET 5开始的Convert.ToHexString。还有一个用于反向操作的方法：Convert.FromHexString。
对于较旧版本的.NET，您可以使用：
public static string ByteArrayToString(byte[] ba)
{
StringBuilder hex = new StringBuilder(ba.Length * 2);
foreach (byte b in ba)
hex.AppendFormat("{0:x2}", b);
return hex.ToString();
}
or:
public static string ByteArrayToString(byte[] ba)
{
return BitConverter.ToString(ba).Replace("-","");
}
举个例子，这里有更多的方法。
反向转换如下：
public static byte[] StringToByteArray(String hex)
{
int NumberChars = hex.Length;
byte[] bytes = new byte[NumberChars / 2];
for (int i = 0; i < NumberChars; i += 2)
bytes[i / 2] = Convert.ToByte(hex.Substring(i, 2), 16);
return bytes;
}
使用Substring是与Convert.ToByte结合使用的最佳选项。有关详细信息，请参阅此答案。如果需要更好的性能，必须避免Convert.ToByte，然后才能删除SubString。
这个问题也可以使用查找表来解决。这将需要编码器和解码器的少量静态存储器。然而，这种方法很快：
编码器表512字节或1024字节（两次大小写（如果是大写和小写）需要）解码器表256字节或64 KiB（单个字符查找或双字符查找）
我的解决方案使用1024字节作为编码表，256字节用于解码。
解码
private static readonly byte[] LookupTable = new byte[] {
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
};
private static byte Lookup(char c)
{
var b = LookupTable[c];
if (b == 255)
throw new IOException("Expected a hex character, got " + c);
return b;
}
public static byte ToByte(char[] chars, int offset)
{
return (byte)(Lookup(chars[offset]) << 4 | Lookup(chars[offset + 1]));
}
编码
private static readonly char[][] LookupTableUpper;
private static readonly char[][] LookupTableLower;
static Hex()
{
LookupTableLower = new char[256][];
LookupTableUpper = new char[256][];
for (var i = 0; i < 256; i++)
{
LookupTableLower[i] = i.ToString("x2").ToCharArray();
LookupTableUpper[i] = i.ToString("X2").ToCharArray();
}
}
public static char[] ToCharLower(byte[] b, int bOffset)
{
return LookupTableLower[b[bOffset]];
}
public static char[] ToCharUpper(byte[] b, int bOffset)
{
return LookupTableUpper[b[bOffset]];
}
比较
StringBuilderToStringFromBytes: 106148
BitConverterToStringFromBytes: 15783
ArrayConvertAllToStringFromBytes: 54290
ByteManipulationToCharArray: 8444
TableBasedToCharArray: 5651 *
*这个解决方案
Note
在解码过程中，可能会发生IOException和IndexOutOfRangeException（如果字符的值太高>256）。应该实现对流或数组进行去/编码的方法，这只是概念的证明。
这里不想赘述很多答案，但我发现了一个十六进制字符串解析器的相当优化（比公认的好4.5倍）、简单的实现。首先，我的测试输出（第一批是我的实现）：
Give me that string:
04c63f7842740c77e545bb0b2ade90b384f119f6ab57b680b7aa575a2f40939f
Time to parse 100,000 times: 50.4192 ms
Result as base64: BMY/eEJ0DHflRbsLKt6Qs4TxGfarV7aAt6pXWi9Ak58=
BitConverter'd: 04-C6-3F-78-42-74-0C-77-E5-45-BB-0B-2A-DE-90-B3-84-F1-19-F6-AB-5
7-B6-80-B7-AA-57-5A-2F-40-93-9F
Accepted answer: (StringToByteArray)
Time to parse 100000 times: 233.1264ms
Result as base64: BMY/eEJ0DHflRbsLKt6Qs4TxGfarV7aAt6pXWi9Ak58=
BitConverter'd: 04-C6-3F-78-42-74-0C-77-E5-45-BB-0B-2A-DE-90-B3-84-F1-19-F6-AB-5
7-B6-80-B7-AA-57-5A-2F-40-93-9F
With Mono's implementation:
Time to parse 100000 times: 777.2544ms
Result as base64: BMY/eEJ0DHflRbsLKt6Qs4TxGfarV7aAt6pXWi9Ak58=
BitConverter'd: 04-C6-3F-78-42-74-0C-77-E5-45-BB-0B-2A-DE-90-B3-84-F1-19-F6-AB-5
7-B6-80-B7-AA-57-5A-2F-40-93-9F
With SoapHexBinary:
Time to parse 100000 times: 845.1456ms
Result as base64: BMY/eEJ0DHflRbsLKt6Qs4TxGfarV7aAt6pXWi9Ak58=
BitConverter'd: 04-C6-3F-78-42-74-0C-77-E5-45-BB-0B-2A-DE-90-B3-84-F1-19-F6-AB-5
7-B6-80-B7-AA-57-5A-2F-40-93-9F
base64和“BitConverter'd”行用于测试正确性。请注意，它们是相等的。
实施：
public static byte[] ToByteArrayFromHex(string hexString)
{
if (hexString.Length % 2 != 0) throw new ArgumentException("String must have an even length");
var array = new byte[hexString.Length / 2];
for (int i = 0; i < hexString.Length; i += 2)
{
array[i/2] = ByteFromTwoChars(hexString[i], hexString[i + 1]);
}
return array;
}
private static byte ByteFromTwoChars(char p, char p_2)
{
byte ret;
if (p <= '9' && p >= '0')
{
ret = (byte) ((p - '0') << 4);
}
else if (p <= 'f' && p >= 'a')
{
ret = (byte) ((p - 'a' + 10) << 4);
}
else if (p <= 'F' && p >= 'A')
{
ret = (byte) ((p - 'A' + 10) << 4);
} else throw new ArgumentException("Char is not a hex digit: " + p,"p");
if (p_2 <= '9' && p_2 >= '0')
{
ret |= (byte) ((p_2 - '0'));
}
else if (p_2 <= 'f' && p_2 >= 'a')
{
ret |= (byte) ((p_2 - 'a' + 10));
}
else if (p_2 <= 'F' && p_2 >= 'A')
{
ret |= (byte) ((p_2 - 'A' + 10));
} else throw new ArgumentException("Char is not a hex digit: " + p_2, "p_2");
return ret;
}
我尝试了一些不安全的东西，并将（显然是冗余的）字符移动到另一个方法来蚕食if序列，但这是最快的。
（我承认这回答了一半的问题。我觉得字符串->字节[]转换不足，而字节[]->字符串角度似乎被很好地覆盖了。因此，这个答案。）
为了提高性能，我会选择drphrozens解决方案。解码器的一个微小的优化可能是为任一字符使用一个表，以消除“<<4”。
显然，这两个方法调用代价高昂。如果对输入或输出数据进行某种检查（可以是CRC、校验和或其他），则If（b==255）。。。可以跳过，从而也可以完全调用方法。
使用offset++和offset代替offset和offset+1可能会带来一些理论上的好处，但我怀疑编译器比我更好地处理这一点。
private static readonly byte[] LookupTableLow = new byte[] {
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
};
private static readonly byte[] LookupTableHigh = new byte[] {
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0x00, 0x10, 0x20, 0x30, 0x40, 0x50, 0x60, 0x70, 0x80, 0x90, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xA0, 0xB0, 0xC0, 0xD0, 0xE0, 0xF0, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xA0, 0xB0, 0xC0, 0xD0, 0xE0, 0xF0, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF
};
private static byte LookupLow(char c)
{
var b = LookupTableLow[c];
if (b == 255)
throw new IOException("Expected a hex character, got " + c);
return b;
}
private static byte LookupHigh(char c)
{
var b = LookupTableHigh[c];
if (b == 255)
throw new IOException("Expected a hex character, got " + c);
return b;
}
public static byte ToByte(char[] chars, int offset)
{
return (byte)(LookupHigh(chars[offset++]) | LookupLow(chars[offset]));
}
这只是我的头顶，没有经过测试或基准测试。
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