Int to byte array

Question

I thought  net had some kind of easy conversion method to use for converting an int into a byte array  I did a quick search and all solutions are bit masking shifting one byte at a time  like  the good ol days    Is there not a ToByteArray   method somewhere

User · Answer

This may be OT but if you are serializing a lot of primitive types or POD structures  Google Protocol Buffers for  Net might be useful to you   This addresses the endianness issue  Marc raised above  among other useful features

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Marc s answer is of course the right answer  But since he mentioned the shift operators and unsafe code as an alternative  I would like to share a less common alternative  Using a struct with Explicit layout  This is similar in principal to a C C   union    Here is an example of a struct that can be used to get to the component bytes of the Int32 data type and the nice thing is that it is two way  you can manipulate the byte values and see the effect on the Int     using System Runtime InteropServices      StructLayout LayoutKind Explicit     struct Int32Converter          FieldOffset 0   public int Value       FieldOffset 0   public byte Byte1       FieldOffset 1   public byte Byte2       FieldOffset 2   public byte Byte3       FieldOffset 3   public byte Byte4       public Int32Converter int value              Byte1   Byte2   Byte3   Byte4   0        Value   value             public static implicit operator Int32 Int32Converter value              return value Value             public static implicit operator Int32Converter int value              return new Int32Converter value               The above can now be used as follows   Int32Converter i32   256   Console WriteLine i32 Byte1    Console WriteLine i32 Byte2    Console WriteLine i32 Byte3    Console WriteLine i32 Byte4     i32 Byte2   2   Console WriteLine i32 Value     Of course the immutability police may not be excited about the last possiblity

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If you came here from Google  Alternative answer to an older question refers to John Skeet s Library that has tools for letting you write primitive data types directly into a byte   with an Index offset  Far better than BitConverter if you need performance   Older thread discussing this issue here  John Skeet s Libraries are here  Just download the source and look at the MiscUtil Conversion namespace   EndianBitConverter cs handles everything for you

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Update for 2020 - BinaryPrimitives should now be preferred over BitConverter  It provides endian-specific APIs  and is less allocatey     byte   bytes   BitConverter GetBytes i     although note also that you might want to check BitConverter IsLittleEndian to see which way around that is going to appear   Note that if you are doing this repeatedly you might want to avoid all those short-lived array allocations by writing it yourself via either shift operations   gt  gt     lt  lt    or by using unsafe code  Shift operations also have the advantage that they aren t affected by your platform s endianness  you always get the bytes in the order you expect them

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Most of the answers here are either  UnSafe  or not LittleEndian safe  BitConverter is not LittleEndian safe  So building on an example in here  see the post by PZahra  I made a LittleEndian safe version simply by reading the byte array in reverse when BitConverter IsLittleEndian    true  void Main            Console WriteLine BitConverter IsLittleEndian        byte   bytes   BitConverter GetBytes 0xdcbaabcdfffe1608         Console WriteLine bytes        string hexStr   ByteArrayToHex bytes       Console WriteLine hexStr      public static string ByteArrayToHex byte   data         char   c   new char data Length   2       byte b     if BitConverter IsLittleEndian                read the byte array in reverse         for  int y   data Length -1  x   0  y  gt   0  --y    x                          b     byte  data y   gt  gt  4                 c x     char  b  gt  9   b   0x37   b   0x30                b     byte  data y   amp  0xF                 c   x     char  b  gt  9   b   0x37   b   0x30                                       else               for  int y   0  x   0  y  lt  data Length    y    x                          b     byte  data y   gt  gt  4                 c x     char  b  gt  9   b   0x37   b   0x30                b     byte  data y   amp  0xF                 c   x     char  b  gt  9   b   0x37   b   0x30                        return String Concat  0x  new string c        It returns this   True 0xDCBAABCDFFFE1608   which is the exact hex that went into the byte array

[c#] Int to byte array

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