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

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。

其他回答

从微软的开发人员那里,一个很好的、简单的转换:

public static string ByteArrayToString(byte[] ba) 
{
    // Concatenate the bytes into one long string
    return ba.Aggregate(new StringBuilder(32),
                            (sb, b) => sb.Append(b.ToString("X2"))
                            ).ToString();
}

虽然上面的内容简洁紧凑,但性能狂热者会使用枚举器对此尖叫不已。通过Tomalak原始答案的改进版本,您可以获得最佳性能:

public static string ByteArrayToString(byte[] ba)   
{   
   StringBuilder hex = new StringBuilder(ba.Length * 2);   

   for(int i=0; i < ba.Length; i++)       // <-- Use for loop is faster than foreach   
       hex.Append(ba[i].ToString("X2"));   // <-- ToString is faster than AppendFormat   

   return hex.ToString();   
} 

这是迄今为止我在这里看到的所有例程中速度最快的。不要只相信我的话…对每个例程进行性能测试并自行检查其CIL代码。

我没有得到你建议的代码,Olipro。hex[i]+hex[i+1]显然返回了int。

然而,我确实从Waleeds代码中得到了一些提示,并将其结合在一起,取得了一些成功。这很难看,但根据我的测试(使用patricges测试机制),与其他测试相比,它似乎有1/3的时间在工作和执行。取决于输入大小。切换?:s首先将0-9分隔开可能会产生稍微更快的结果,因为数字比字母多。

public static byte[] StringToByteArray2(string hex)
{
    byte[] bytes = new byte[hex.Length/2];
    int bl = bytes.Length;
    for (int i = 0; i < bl; ++i)
    {
        bytes[i] = (byte)((hex[2 * i] > 'F' ? hex[2 * i] - 0x57 : hex[2 * i] > '9' ? hex[2 * i] - 0x37 : hex[2 * i] - 0x30) << 4);
        bytes[i] |= (byte)(hex[2 * i + 1] > 'F' ? hex[2 * i + 1] - 0x57 : hex[2 * i + 1] > '9' ? hex[2 * i + 1] - 0x37 : hex[2 * i + 1] - 0x30);
    }
    return bytes;
}

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

用@CodesInChaus补充答案(反向方法)

public static byte[] HexToByteUsingByteManipulation(string s)
{
    byte[] bytes = new byte[s.Length / 2];
    for (int i = 0; i < bytes.Length; i++)
    {
        int hi = s[i*2] - 65;
        hi = hi + 10 + ((hi >> 31) & 7);

        int lo = s[i*2 + 1] - 65;
        lo = lo + 10 + ((lo >> 31) & 7) & 0x0f;

        bytes[i] = (byte) (lo | hi << 4);
    }
    return bytes;
}

说明:

&0x0f还支持小写字母

hi=hi+10+((hi>>31)&7);与以下内容相同:

hi=ch-65+10+((ch-65)>>31)&7);

对于“0”9’与hi=ch-65+10+7相同;其为hi=ch-48(这是因为0xffffff&7)。

对于“A”F’为hi=ch-65+10;(这是因为0x00000000&7)。

对于“a”我们必须使用大数字,所以我们必须通过使用&0x0f使某些位为0,从默认版本中减去32。

65是“A”的代码

48是“0”的代码

7是ASCII表中“9”和“A”之间的字母数(…456789:;<=>?@ABCD…)。

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();