非常快速的扩展方法(带反转):

public static class ExtensionMethods {
    public static string ToHex(this byte[] data) {
        return ToHex(data, "");
    }
    public static string ToHex(this byte[] data, string prefix) {
        char[] lookup = new char[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
        int i = 0, p = prefix.Length, l = data.Length;
        char[] c = new char[l * 2 + p];
        byte d;
        for(; i < p; ++i) c[i] = prefix[i];
        i = -1;
        --l;
        --p;
        while(i < l) {
            d = data[++i];
            c[++p] = lookup[d >> 4];
            c[++p] = lookup[d & 0xF];
        }
        return new string(c, 0, c.Length);
    }
    public static byte[] FromHex(this string str) {
        return FromHex(str, 0, 0, 0);
    }
    public static byte[] FromHex(this string str, int offset, int step) {
        return FromHex(str, offset, step, 0);
    }
    public static byte[] FromHex(this string str, int offset, int step, int tail) {
        byte[] b = new byte[(str.Length - offset - tail + step) / (2 + step)];
        byte c1, c2;
        int l = str.Length - tail;
        int s = step + 1;
        for(int y = 0, x = offset; x < l; ++y, x += s) {
            c1 = (byte)str[x];
            if(c1 > 0x60) c1 -= 0x57;
            else if(c1 > 0x40) c1 -= 0x37;
            else c1 -= 0x30;
            c2 = (byte)str[++x];
            if(c2 > 0x60) c2 -= 0x57;
            else if(c2 > 0x40) c2 -= 0x37;
            else c2 -= 0x30;
            b[y] = (byte)((c1 << 4) + c2);
        }
        return b;
    }
}

在上面的速度测试中击败所有其他人:

=== Long string test BitConvertReplace calculation Time Elapsed 2415 ms StringBuilder calculation Time Elapsed 5668 ms LinqConcat calculation Time Elapsed 11826 ms LinqJoin calculation Time Elapsed 9323 ms LinqAgg calculation Time Elapsed 7444 ms ToHexTable calculation Time Elapsed 1028 ms ToHexAcidzombie calculation Time Elapsed 1035 ms ToHexPatrick calculation Time Elapsed 814 ms ToHexKurt calculation Time Elapsed 1604 ms ByteArrayToHexString calculation Time Elapsed 1330 ms === Many string test BitConvertReplace calculation Time Elapsed 2238 ms StringBuilder calculation Time Elapsed 5393 ms LinqConcat calculation Time Elapsed 9043 ms LinqJoin calculation Time Elapsed 9131 ms LinqAgg calculation Time Elapsed 7324 ms ToHexTable calculation Time Elapsed 968 ms ToHexAcidzombie calculation Time Elapsed 969 ms ToHexPatrick calculation Time Elapsed 956 ms ToHexKurt calculation Time Elapsed 1547 ms ByteArrayToHexString calculation Time Elapsed 1277 ms

你必须知道以字节表示的字符串的编码，但是你可以说System.Text.UTF8Encoding.GetString(字节)或System.Text.ASCIIEncoding.GetString(字节)。(我是根据记忆做的，所以API可能不完全正确，但它非常接近。)

第二个问题的答案，请看这个问题。

我想我做了一个更快的字节数组到字符串转换器:

public static class HexTable
{
    private static readonly string[] table = BitConverter.ToString(Enumerable.Range(0, 256).Select(x => (byte)x).ToArray()).Split('-');

    public static string ToHexTable(byte[] value)
    {
        StringBuilder sb = new StringBuilder(2 * value.Length);

        for (int i = 0; i < value.Length; i++)
            sb.Append(table[value[i]]);

        return sb.ToString();
    }

并且测试设置:

static void Main(string[] args)
{
        const int TEST_COUNT = 10000;
        const int BUFFER_LENGTH = 100000;

        Random random = new Random();

        Stopwatch sw = new Stopwatch();
        Stopwatch sw2 = new Stopwatch();

        byte[] buffer = new byte[BUFFER_LENGTH];
        random.NextBytes(buffer);

        sw.Start();
        for (int j = 0; j < TEST_COUNT; j++)
            HexTable.ToHexTable(buffer);

        sw.Stop();

        sw2.Start();
        for (int j = 0; j < TEST_COUNT; j++)
            ToHexChar.ToHex(buffer);

        sw2.Stop();

        Console.WriteLine("Hex Table Elapsed Milliseconds: {0}", sw.ElapsedMilliseconds);
        Console.WriteLine("ToHex Elapsed Milliseconds: {0}", sw2.ElapsedMilliseconds);
    }

ToHexChar.ToHEx()方法是前面所示的ToHex()方法。

结果如下:

HexTable = 11808 ms ToHEx = 12168ms

它看起来可能没有太大的不同，但它仍然更快:)

再向这个堆中添加一个答案，有一个System.Runtime.Remoting.Metadata.W3cXsd2001。SoapHexBinary类，我已经使用它可以转换字节和十六进制:

string hex = new SoapHexBinary(bytes).ToString();
byte[] bytes = SoapHexBinary.Parse(hex).Value;

不确定它与其他实现(基准)相比如何，但在我看来，它非常简单——特别是从十六进制转换回字节。

:

byte[] data = new byte[] { 0x01, 0x02, 0x03, 0x0D, 0x0E, 0x0F };
string hex = string.Empty;
data.ToList().ForEach(b => hex += b.ToString("x2"));
// use "X2" for uppercase hex letters
Console.WriteLine(hex);

结果:0102030 d0e0f

我喜欢将扩展方法用于这样的转换，即使它们只是包装标准库方法。在十六进制转换的情况下，我使用以下手动调优(即快速)算法:

public static string ToHex(this byte[] bytes)
{
    char[] c = new char[bytes.Length * 2];

    byte b;

    for(int bx = 0, cx = 0; bx < bytes.Length; ++bx, ++cx) 
    {
        b = ((byte)(bytes[bx] >> 4));
        c[cx] = (char)(b > 9 ? b + 0x37 + 0x20 : b + 0x30);

        b = ((byte)(bytes[bx] & 0x0F));
        c[++cx]=(char)(b > 9 ? b + 0x37 + 0x20 : b + 0x30);
    }

    return new string(c);
}

public static byte[] HexToBytes(this string str)
{
    if (str.Length == 0 || str.Length % 2 != 0)
        return new byte[0];

    byte[] buffer = new byte[str.Length / 2];
    char c;
    for (int bx = 0, sx = 0; bx < buffer.Length; ++bx, ++sx)
    {
        // Convert first half of byte
        c = str[sx];
        buffer[bx] = (byte)((c > '9' ? (c > 'Z' ? (c - 'a' + 10) : (c - 'A' + 10)) : (c - '0')) << 4);

        // Convert second half of byte
        c = str[++sx];
        buffer[bx] |= (byte)(c > '9' ? (c > 'Z' ? (c - 'a' + 10) : (c - 'A' + 10)) : (c - '0'));
    }

    return buffer;
}