How can I convert a hex string to a byte array

Question

Can we convert a hex string to a byte array using a built-in function in C  or do I have to make a custom method for this

User · Accepted Answer

Here s a nice fun LINQ example   public static byte   StringToByteArray string hex        return Enumerable Range 0  hex Length                        Where x   gt  x   2    0                        Select x   gt  Convert ToByte hex Substring x  2   16                         ToArray

User · Answer

I did some research and found out that byte Parse is even slower than Convert ToByte  The fastest conversion I could come up with uses approximately 15 ticks per byte       public static byte   StringToByteArrayFastest string hex            if  hex Length   2    1              throw new Exception  The binary key cannot have an odd number of digits             byte   arr   new byte hex Length  gt  gt  1            for  int i   0  i  lt  hex Length  gt  gt  1    i                        arr i     byte   GetHexVal hex i  lt  lt  1    lt  lt  4     GetHexVal hex  i  lt  lt  1    1                         return arr             public static int GetHexVal char hex            int val    int hex            For uppercase A-F letters            return val -  val  lt  58   48   55             For lowercase a-f letters            return val -  val  lt  58   48   87             Or the two combined  but a bit slower          return val -  val  lt  58   48    val  lt  97   55   87               also works on  NET Micro Framework where  in SDK4 3  byte Parse string  only permits integer formats

User · Answer

I did some research and found out that byte Parse is even slower than Convert ToByte  The fastest conversion I could come up with uses approximately 15 ticks per byte       public static byte   StringToByteArrayFastest string hex            if  hex Length   2    1              throw new Exception  The binary key cannot have an odd number of digits             byte   arr   new byte hex Length  gt  gt  1            for  int i   0  i  lt  hex Length  gt  gt  1    i                        arr i     byte   GetHexVal hex i  lt  lt  1    lt  lt  4     GetHexVal hex  i  lt  lt  1    1                         return arr             public static int GetHexVal char hex            int val    int hex            For uppercase A-F letters            return val -  val  lt  58   48   55             For lowercase a-f letters            return val -  val  lt  58   48   87             Or the two combined  but a bit slower          return val -  val  lt  58   48    val  lt  97   55   87               also works on  NET Micro Framework where  in SDK4 3  byte Parse string  only permits integer formats

User · Answer

The following code changes the hexadecimal string to a byte array by parsing the string byte-by-byte   public static byte   ConvertHexStringToByteArray string hexString        if  hexString Length   2    0                throw new ArgumentException String Format CultureInfo InvariantCulture   The binary key cannot have an odd number of digits   0    hexString               byte   data   new byte hexString Length   2       for  int index   0  index  lt  data Length  index                  string byteValue   hexString Substring index   2  2           data index    byte Parse byteValue  NumberStyles HexNumber  CultureInfo InvariantCulture              return data

User · Answer

The following code changes the hexadecimal string to a byte array by parsing the string byte-by-byte   public static byte   ConvertHexStringToByteArray string hexString        if  hexString Length   2    0                throw new ArgumentException String Format CultureInfo InvariantCulture   The binary key cannot have an odd number of digits   0    hexString               byte   data   new byte hexString Length   2       for  int index   0  index  lt  data Length  index                  string byteValue   hexString Substring index   2  2           data index    byte Parse byteValue  NumberStyles HexNumber  CultureInfo InvariantCulture              return data

User · Answer

I think this may work   public static byte   StrToByteArray string str                Dictionary lt string  byte gt  hexindex   new Dictionary lt string  byte gt             for  int i   0  i  lt   255  i                hexindex Add i ToString  X2     byte i            List lt byte gt  hexres   new List lt byte gt             for  int i   0  i  lt  str Length  i    2                          hexres Add hexindex str Substring i  2              return hexres ToArray

User · Answer

I think this may work   public static byte   StrToByteArray string str                Dictionary lt string  byte gt  hexindex   new Dictionary lt string  byte gt             for  int i   0  i  lt   255  i                hexindex Add i ToString  X2     byte i            List lt byte gt  hexres   new List lt byte gt             for  int i   0  i  lt  str Length  i    2                          hexres Add hexindex str Substring i  2              return hexres ToArray

[c#] How can I convert a hex string to a byte array?

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