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
另一种基于查找表的方法。该方法只为每个字节使用一个查找表,而不是为每个半字节使用查找表。
private static readonly uint[] _lookup32 = CreateLookup32();
private static uint[] CreateLookup32()
{
var result = new uint[256];
for (int i = 0; i < 256; i++)
{
string s=i.ToString("X2");
result[i] = ((uint)s[0]) + ((uint)s[1] << 16);
}
return result;
}
private static string ByteArrayToHexViaLookup32(byte[] bytes)
{
var lookup32 = _lookup32;
var result = new char[bytes.Length * 2];
for (int i = 0; i < bytes.Length; i++)
{
var val = lookup32[bytes[i]];
result[2*i] = (char)val;
result[2*i + 1] = (char) (val >> 16);
}
return new string(result);
}
我还使用查找表中的ushort、struct{char X1,X2}、struct{byte X1,X2}测试了这个变体。
根据编译目标(x86、X64)的不同,它们要么具有大致相同的性能,要么稍慢于此变体。
为了获得更高的性能,其不安全的兄弟:
private static readonly uint[] _lookup32Unsafe = CreateLookup32Unsafe();
private static readonly uint* _lookup32UnsafeP = (uint*)GCHandle.Alloc(_lookup32Unsafe,GCHandleType.Pinned).AddrOfPinnedObject();
private static uint[] CreateLookup32Unsafe()
{
var result = new uint[256];
for (int i = 0; i < 256; i++)
{
string s=i.ToString("X2");
if(BitConverter.IsLittleEndian)
result[i] = ((uint)s[0]) + ((uint)s[1] << 16);
else
result[i] = ((uint)s[1]) + ((uint)s[0] << 16);
}
return result;
}
public static string ByteArrayToHexViaLookup32Unsafe(byte[] bytes)
{
var lookupP = _lookup32UnsafeP;
var result = new char[bytes.Length * 2];
fixed(byte* bytesP = bytes)
fixed (char* resultP = result)
{
uint* resultP2 = (uint*)resultP;
for (int i = 0; i < bytes.Length; i++)
{
resultP2[i] = lookupP[bytesP[i]];
}
}
return new string(result);
}
或者如果您认为可以直接写入字符串:
public static string ByteArrayToHexViaLookup32UnsafeDirect(byte[] bytes)
{
var lookupP = _lookup32UnsafeP;
var result = new string((char)0, bytes.Length * 2);
fixed (byte* bytesP = bytes)
fixed (char* resultP = result)
{
uint* resultP2 = (uint*)resultP;
for (int i = 0; i < bytes.Length; i++)
{
resultP2[i] = lookupP[bytesP[i]];
}
}
return result;
}
其他回答
Dotnet 5更新
要从byte[](字节数组)转换为十六进制字符串,请使用:
System.Convert.ToHexString
var myBytes = new byte[100];
var myString = System.Convert.ToHexString(myBytes);
要将十六进制字符串转换为字节[],请使用:
System.Convert.FromHexString
var myString = "E10B116E8530A340BCC7B3EAC208487B";
var myBytes = System.Convert.FromHexString(myString);
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…)。
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。
为了方便以后复制和粘贴,将几个答案合并到一个类中:
/// <summary>
/// Extension methods to quickly convert byte array to string and back.
/// </summary>
public static class HexConverter
{
/// <summary>
/// Map values to hex digits
/// </summary>
private static readonly char[] HexDigits =
{
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
};
/// <summary>
/// Map 56 characters between ['0', 'F'] to their hex equivalents, and set invalid characters
/// such that they will overflow byte to fail conversion.
/// </summary>
private static readonly ushort[] HexValues =
{
0x0000, 0x0001, 0x0002, 0x0003, 0x0004, 0x0005, 0x0006, 0x0007, 0x0008, 0x0009, 0x0100, 0x0100, 0x0100, 0x0100, 0x0100, 0x0100, 0x0100,
0x000A, 0x000B, 0x000C, 0x000D, 0x000E, 0x000F, 0x0100, 0x0100, 0x0100, 0x0100, 0x0100, 0x0100, 0x0100, 0x0100, 0x0100, 0x0100, 0x0100,
0x0100, 0x0100, 0x0100, 0x0100, 0x0100, 0x0100, 0x0100, 0x0100, 0x0100, 0x0100, 0x0100, 0x0100, 0x0100, 0x0100, 0x0100, 0x000A, 0x000B,
0x000C, 0x000D, 0x000E, 0x000F
};
/// <summary>
/// Empty byte array
/// </summary>
private static readonly byte[] Empty = new byte[0];
/// <summary>
/// Convert a byte array to a hexadecimal string.
/// </summary>
/// <param name="bytes">
/// The input byte array.
/// </param>
/// <returns>
/// A string of hexadecimal digits.
/// </returns>
public static string ToHexString(this byte[] bytes)
{
var c = new char[bytes.Length * 2];
for (int i = 0, j = 0; i < bytes.Length; i++)
{
c[j++] = HexDigits[bytes[i] >> 4];
c[j++] = HexDigits[bytes[i] & 0x0F];
}
return new string(c);
}
/// <summary>
/// Parse a string of hexadecimal digits into a byte array.
/// </summary>
/// <param name="hexadecimalString">
/// The hexadecimal string.
/// </param>
/// <returns>
/// The parsed <see cref="byte[]"/> array.
/// </returns>
/// <exception cref="ArgumentException">
/// The input string either contained invalid characters, or was of an odd length.
/// </exception>
public static byte[] ToByteArray(string hexadecimalString)
{
if (!TryParse(hexadecimalString, out var value))
{
throw new ArgumentException("Invalid hexadecimal string", nameof(hexadecimalString));
}
return value;
}
/// <summary>
/// Parse a hexadecimal string to bytes
/// </summary>
/// <param name="hexadecimalString">
/// The hexadecimal string, which must be an even number of characters.
/// </param>
/// <param name="value">
/// The parsed value if successful.
/// </param>
/// <returns>
/// True if successful.
/// </returns>
public static bool TryParse(string hexadecimalString, out byte[] value)
{
if (hexadecimalString.Length == 0)
{
value = Empty;
return true;
}
if (hexadecimalString.Length % 2 != 0)
{
value = Empty;
return false;
}
try
{
value = new byte[hexadecimalString.Length / 2];
for (int i = 0, j = 0; j < hexadecimalString.Length; i++)
{
value[i] = (byte)((HexValues[hexadecimalString[j++] - '0'] << 4)
| HexValues[hexadecimalString[j++] - '0']);
}
return true;
}
catch (OverflowException)
{
value = Empty;
return false;
}
}
}
从.NET 5 RC2开始,您可以使用:
Convert.ToHexString(byte[]inArray),返回字符串和Convert.FromHexString(字符串s),返回字节[]。
可以使用跨度参数的重载。
推荐文章
- 实体框架核心:在上一个操作完成之前,在此上下文中开始的第二个操作
- 如何为构造函数定制Visual Studio的私有字段生成快捷方式?
- 如何使用JSON确保字符串是有效的JSON。网
- 使用C返回一个数组
- AppSettings从.config文件中获取值
- 通过HttpClient向REST API发布一个空体
- 如何检查IEnumerable是否为空或空?
- 自动化invokerrequired代码模式
- 在c#代码中设置WPF文本框的背景颜色
- 在c#中,什么是单子?
- c#和Java中的泛型有什么不同?和模板在c++ ?
- 向对象数组添加属性
- c#线程安全快速(est)计数器
- 如何将此foreach代码转换为Parallel.ForEach?
- 如何分裂()一个分隔字符串到一个列表<字符串>