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
另一个快速功能。。。
private static readonly byte[] HexNibble = new byte[] {
0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7,
0x8, 0x9, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
0x0, 0xA, 0xB, 0xC, 0xD, 0xE, 0xF, 0x0,
0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
0x0, 0xA, 0xB, 0xC, 0xD, 0xE, 0xF
};
public static byte[] HexStringToByteArray( string str )
{
int byteCount = str.Length >> 1;
byte[] result = new byte[byteCount + (str.Length & 1)];
for( int i = 0; i < byteCount; i++ )
result[i] = (byte) (HexNibble[str[i << 1] - 48] << 4 | HexNibble[str[(i << 1) + 1] - 48]);
if( (str.Length & 1) != 0 )
result[byteCount] = (byte) HexNibble[str[str.Length - 1] - 48];
return result;
}
其他回答
测试：十六进制字符串到字节数组
我注意到，大多数测试都是在将Bytes数组转换为十六进制字符串的函数上执行的。因此，在这篇文章中，我将关注另一方面：将十六进制字符串转换为字节数组的函数。若您只对结果感兴趣，可以跳到“摘要”部分。测试代码文件在文章末尾提供。
标签
我想根据接受的答案（Tomalak）将函数命名为StringToByteArrayV1，或将其快捷到V1。其余函数将以相同的方式命名：V2、V3、V4、…、。。。，等
参与功能索引
Tomalak的StringToByteArrayV1（公认答案）Mykroft的StringToByteArrayV2（使用SoapHexBinary）drphrozen的StringToByteArrayV3（查找表）CoperNick的StringToByteArrayV4（字节操作）Chris F编写的StringToByteArrayV5_1（字节操作）Chris F的StringToByteArrayV5_2（V5_1+根据Amir Rezaei的评论修改）Chris F的StringToByteArrayV5_3（V5_2+根据Ben Voigt的评论对其进行了修改）（您可以在发布后的测试代码中看到它的最终形状）Ben Mosher编写的StringToByteArrayV6（字节操作）Maratius的StringToByteArrayV7（字节操作-安全版本）Maratius的StringToByteArrayV8（字节操作-不安全版本）StringToByteArrayV9（按Geograph）AlejandroAlis编写的StringToByteArrayV10Fredrik Hu编写的StringToByteArrayV11Maarten Bodewes编写的StringToByteArrayV12ClausAndersen编写的StringToByteArrayV13Stas Makutin编写的StringToByteArrayV14JJJ的StringToByteArrayV15JamieSee的StringToByteArrayV16spacepille的StringToByteArrayV17Gregory Morse编写的StringToByteArrayV18Rick编写的StringToByteArrayV19SandRock的StringToByteArrayV20Paul编写的StringToByteArrayV21
正确性测试
我通过传递1字节的所有256个可能值来测试正确性，然后检查输出是否正确。结果：
V18中以“00”开头的字符串有问题（请参阅Roger Stewart对此的评论）。除了通过所有测试。如果十六进制字符串字母是大写的：所有函数都成功传递如果十六进制字符串字母是小写的，则以下函数失败：V5_1、V5_2、v7、V8、V15、V19
注：V5_3解决了这个问题（V5_1和V5_2）
性能测试
我已经使用Stopwatch类进行了性能测试。
长字符串的性能
input length: 10,000,000 bytes
runs: 100
average elapsed time per run:
V1 = 136.4ms
V2 = 104.5ms
V3 = 22.0ms
V4 = 9.9ms
V5_1 = 10.2ms
V5_2 = 9.0ms
V5_3 = 9.3ms
V6 = 18.3ms
V7 = 9.8ms
V8 = 8.8ms
V9 = 10.2ms
V10 = 19.0ms
V11 = 12.2ms
V12 = 27.4ms
V13 = 21.8ms
V14 = 12.0ms
V15 = 14.9ms
V16 = 15.3ms
V17 = 9.5ms
V18 got excluded from this test, because it was very slow when using very long string
V19 = 222.8ms
V20 = 66.0ms
V21 = 15.4ms
V1 average ticks per run: 1363529.4
V2 is more fast than V1 by: 1.3 times (ticks ratio)
V3 is more fast than V1 by: 6.2 times (ticks ratio)
V4 is more fast than V1 by: 13.8 times (ticks ratio)
V5_1 is more fast than V1 by: 13.3 times (ticks ratio)
V5_2 is more fast than V1 by: 15.2 times (ticks ratio)
V5_3 is more fast than V1 by: 14.8 times (ticks ratio)
V6 is more fast than V1 by: 7.4 times (ticks ratio)
V7 is more fast than V1 by: 13.9 times (ticks ratio)
V8 is more fast than V1 by: 15.4 times (ticks ratio)
V9 is more fast than V1 by: 13.4 times (ticks ratio)
V10 is more fast than V1 by: 7.2 times (ticks ratio)
V11 is more fast than V1 by: 11.1 times (ticks ratio)
V12 is more fast than V1 by: 5.0 times (ticks ratio)
V13 is more fast than V1 by: 6.3 times (ticks ratio)
V14 is more fast than V1 by: 11.4 times (ticks ratio)
V15 is more fast than V1 by: 9.2 times (ticks ratio)
V16 is more fast than V1 by: 8.9 times (ticks ratio)
V17 is more fast than V1 by: 14.4 times (ticks ratio)
V19 is more SLOW than V1 by: 1.6 times (ticks ratio)
V20 is more fast than V1 by: 2.1 times (ticks ratio)
V21 is more fast than V1 by: 8.9 times (ticks ratio)
V18的长串性能
V18 took long time at the previous test,
so let's decrease length for it:
input length: 1,000,000 bytes
runs: 100
average elapsed time per run: V1 = 14.1ms , V18 = 146.7ms
V1 average ticks per run: 140630.3
V18 is more SLOW than V1 by: 10.4 times (ticks ratio)
短字符串的性能
input length: 100 byte
runs: 1,000,000
V1 average ticks per run: 14.6
V2 is more fast than V1 by: 1.4 times (ticks ratio)
V3 is more fast than V1 by: 5.9 times (ticks ratio)
V4 is more fast than V1 by: 15.7 times (ticks ratio)
V5_1 is more fast than V1 by: 15.1 times (ticks ratio)
V5_2 is more fast than V1 by: 18.4 times (ticks ratio)
V5_3 is more fast than V1 by: 16.3 times (ticks ratio)
V6 is more fast than V1 by: 5.3 times (ticks ratio)
V7 is more fast than V1 by: 15.7 times (ticks ratio)
V8 is more fast than V1 by: 18.0 times (ticks ratio)
V9 is more fast than V1 by: 15.5 times (ticks ratio)
V10 is more fast than V1 by: 7.8 times (ticks ratio)
V11 is more fast than V1 by: 12.4 times (ticks ratio)
V12 is more fast than V1 by: 5.3 times (ticks ratio)
V13 is more fast than V1 by: 5.2 times (ticks ratio)
V14 is more fast than V1 by: 13.4 times (ticks ratio)
V15 is more fast than V1 by: 9.9 times (ticks ratio)
V16 is more fast than V1 by: 9.2 times (ticks ratio)
V17 is more fast than V1 by: 16.2 times (ticks ratio)
V18 is more fast than V1 by: 1.1 times (ticks ratio)
V19 is more SLOW than V1 by: 1.6 times (ticks ratio)
V20 is more fast than V1 by: 1.9 times (ticks ratio)
V21 is more fast than V1 by: 11.4 times (ticks ratio)
测试代码
在使用以下代码之前，最好先阅读本文下面的免责声明部分https://github.com/Ghosticollis/performance-tests/blob/main/MTestPerformance.cs
总结
由于性能良好，我建议使用以下函数之一，并支持大写和小写：
CoperNick的StringToByteArrayV4StringToByteArrayV9（按Geograph）spacepille的StringToByteArrayV17StringToByteArrayV5_3基本上由Chris F开发（它基于V5_1，但我根据Amir Rezaei和Ben Voigt的评论对其进行了增强）。
以下是V5_3的最终形状：
static byte[] HexStringToByteArrayV5_3(string hexString) {
int hexStringLength = hexString.Length;
byte[] b = new byte[hexStringLength / 2];
for (int i = 0; i < hexStringLength; i += 2) {
int topChar = hexString[i];
topChar = (topChar > 0x40 ? (topChar & ~0x20) - 0x37 : topChar - 0x30) << 4;
int bottomChar = hexString[i + 1];
bottomChar = bottomChar > 0x40 ? (bottomChar & ~0x20) - 0x37 : bottomChar - 0x30;
b[i / 2] = (byte)(topChar + bottomChar);
}
return b;
}
免责声明
警告：我没有适当的测试知识。这些原始测试的主要目的是快速概述所有发布的函数的优点。如果您需要准确的结果，请使用适当的测试工具。
最后，我想说，我是新来的，在斯塔科弗洛活跃，如果我的职位空缺，我很抱歉。如果您能发表评论，我们将不胜感激。
static string ByteArrayToHexViaLookupPerByte2(byte[] bytes)
{
var result3 = new uint[bytes.Length];
for (int i = 0; i < bytes.Length; i++)
result3[i] = _Lookup32[bytes[i]];
var handle = GCHandle.Alloc(result3, GCHandleType.Pinned);
try
{
var result = Marshal.PtrToStringUni(handle.AddrOfPinnedObject(), bytes.Length * 2);
return result;
}
finally
{
handle.Free();
}
}
在我的测试中，这个函数总是不安全实现之后的第二个条目。
不幸的是，测试台不太可靠。。。如果你多次运行它，列表会被打乱，以至于谁知道在不安全之后哪个才是最快的！它没有考虑预热、jit编译时间和GC性能影响。我很想重写它以获得更多信息，但我真的没有时间。
这是我的尝试。我创建了一对扩展类来扩展字符串和字节。在大文件测试中，性能与Byte Manipulation 2相当。
下面的ToHexString代码是查找和移位算法的优化实现。它与Behrooz的方法几乎相同，但使用foreach进行迭代，计数器比显式索引更快。
在我的机器上，它排在Byte Manipulation 2之后，排在第二位，是非常可读的代码。以下测试结果也值得关注：
ToHexStringCharArrayWithCharArrayLookup：41589.69平均刻度（超过1000次），1.5倍ToHexStringCharArrayWithStringLookup:50764.06平均滴答（超过1000次），1.2XToHexStringStringBuilderWithCharArrayLookup:62812.87平均滴答（超过1000次），1.0X
根据上述结果，可以得出以下结论：
索引到字符串以执行查找与char数组在大型文件测试中非常重要。使用已知容量的StringBuilder与使用字符的惩罚创建字符串的已知大小的数组甚至更重要。
代码如下：
using System;
namespace ConversionExtensions
{
public static class ByteArrayExtensions
{
private readonly static char[] digits = new char[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
public static string ToHexString(this byte[] bytes)
{
char[] hex = new char[bytes.Length * 2];
int index = 0;
foreach (byte b in bytes)
{
hex[index++] = digits[b >> 4];
hex[index++] = digits[b & 0x0F];
}
return new string(hex);
}
}
}
using System;
using System.IO;
namespace ConversionExtensions
{
public static class StringExtensions
{
public static byte[] ToBytes(this string hexString)
{
if (!string.IsNullOrEmpty(hexString) && hexString.Length % 2 != 0)
{
throw new FormatException("Hexadecimal string must not be empty and must contain an even number of digits to be valid.");
}
hexString = hexString.ToUpperInvariant();
byte[] data = new byte[hexString.Length / 2];
for (int index = 0; index < hexString.Length; index += 2)
{
int highDigitValue = hexString[index] <= '9' ? hexString[index] - '0' : hexString[index] - 'A' + 10;
int lowDigitValue = hexString[index + 1] <= '9' ? hexString[index + 1] - '0' : hexString[index + 1] - 'A' + 10;
if (highDigitValue < 0 || lowDigitValue < 0 || highDigitValue > 15 || lowDigitValue > 15)
{
throw new FormatException("An invalid digit was encountered. Valid hexadecimal digits are 0-9 and A-F.");
}
else
{
byte value = (byte)((highDigitValue << 4) | (lowDigitValue & 0x0F));
data[index / 2] = value;
}
}
return data;
}
}
}
下面是当我将代码放在我机器上的@patridge测试项目中时得到的测试结果。我还添加了一个从十六进制转换为字节数组的测试。使用我的代码的测试运行是ByteArrayToHexViaOptimizedLookupAndShift和HexToByteArrayViaByteManipulation。HexToByteArrayViaConvertToByte取自XXXX。HexToByteArrayViaSoapHexBinary是@Mykroft的答案。
Intel Pentium III Xeon处理器核心：4<br/>当前时钟速度：1576<br/>最大时钟速度：3092<br/>将字节数组转换为十六进制字符串表示ByteArrayToHexViaByteManipulation2:39366.64平均滴答（超过1000次），22.4倍ByteArrayToHexViaOptimizedLookupAndShift：41588.64平均刻度（超过1000次），21.2倍ByteArrayToHexViaLookup：55509.56次平均点击（超过1000次），15.9倍ByteArrayToHexViaByteManipulation:65349.12平均刻度（超过1000次），13.5XByteArrayToHexViaLookupAndShift：86926.87平均刻度（超过1000运行），10.2XByteArrayToHexStringViaBitConverter:平均139353.73滴答声（超过1000次），6.3XByteArrayToHexViaSoapHexBinary：314598.77平均刻度（超过1000次），2.8XByteArrayToHexStringViaStringBuilderForEachByteToString:344264.63平均刻度（超过1000次），2.6XByteArrayToHexStringViaStringBuilderAggregateByteToString:382623.44平均滴答声（超过1000次），2.3XByteArrayToHexStringViaStringBuilderForEachAppend格式：818111.95平均滴答声（超过1000次），1.1倍ByteArrayToHexStringViaStringConcatArray ConvertAll:839424.84平均值滴答声（超过1000次），1.1XByteArrayToHexStringViaStringBuilderAggregateAppend格式：867303.98平均刻度（超过1000次），1.0XByteArrayToHexStringViaStringJoinArray ConvertAll:平均882710.28滴答声（超过1000次），1.0X
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。
此版本的ByteArrayToHexViaByteManipulation可能更快。
从我的报告中：
ByteArrayToHexViaByteManipulation3:1.68次平均滴答声（超过1000次），17,5XByteArrayToHexViaByteManipulation2:1,73平均滴答（超过1000次），16,9XByteArrayToHexViaByteManipulation:2,90平均刻度（超过1000次），10,1XByteArrayToHexViaLookupAndShift:3.22平均刻度（超过1000次），9,1X...静态专用只读字符[]hexAlphabet=新字符[]{'0'，'1'，'2'，'3'，'4'，'5'，'6'，'7'，'8'，'9'，'A'，'B'，'C'，'D'，'E'，'F'}；静态字符串ByteArrayToHexViaByteManipulation3（byte[]字节）{char[]c=新字符[bytes.Length*2]；字节b；for（int i=0；i<bytes.Length；i++）{b=（（字节）（字节[i]>>4））；c[i*2]=十六进制字母[b]；b=（（字节）（字节[i]&0xF））；c[i*2+1]=十六进制字母[b]；}返回新字符串（c）；}
我认为这是一个优化：
static private readonly char[] hexAlphabet = new char[]
{'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};
static string ByteArrayToHexViaByteManipulation4(byte[] bytes)
{
char[] c = new char[bytes.Length * 2];
for (int i = 0, ptr = 0; i < bytes.Length; i++, ptr += 2)
{
byte b = bytes[i];
c[ptr] = hexAlphabet[b >> 4];
c[ptr + 1] = hexAlphabet[b & 0xF];
}
return new string(c);
}
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