Does C# support struct bit definitions?

Question

Does C# support struct bit definitions?.

For example is there a way to declare a structure like this in c#.net?

typedef struct

{

UINT16 SrcPort;

UINT16 DstPort;

UINT32 SeqNum;

UINT32 AckNum;

UINT16 Reserved1:4;

UINT16 HdrLength:4;

UINT16 Fin:1;

UINT16 Syn:1;

UINT16 Rst:1;

UINT16 Psh:1;

UINT16 Ack:1;

UINT16 Urg:1;

UINT16 Reserved2:2;

UINT16 Window;

UINT16 Checksum;

UINT16 UrgPtr;

} DIVERT_TCPHDR

Please help me to solve this issue? It is very urgent.

How can we set bit position in a C# Structure ?

Vulpes · Answer

Try this: using System; using System.Runtime.InteropServices; [StructLayout(LayoutKind.Sequential)] public struct DIVERT_TCPHDR { public ushort SrcPort; public ushort DstPort; public uint SeqNum; public uint AckNum; public ushort BitField; public ushort Window; public ushort Checksum; public ushort UrgPtr; public byte Reserved1 { get {return (byte)((BitField >> 12) & 15);} set {BitField = (ushort)(BitField & ~(15 } public byte HdrLength { get {return (byte)((BitField >> 8) & 15);} set {BitField = (ushort)(BitField & ~(15 } public byte Fin { get {return (byte)((BitField >> 7) & 1);} set {BitField = (ushort)(BitField & ~(1 } public byte Syn { get {return (byte)((BitField >> 6) & 1);} set {BitField = (ushort)(BitField & ~(1 } public byte Rst { get {return (byte)((BitField >> 5) & 1);} set {BitField = (ushort)(BitField & ~(1 } public byte Psh { get {return (byte)((BitField >> 4) & 1);} set {BitField = (ushort)(BitField & ~(1 } public byte Ack { get {return (byte)((BitField >> 3) & 1);} set {BitField = (ushort)(BitField & ~(1 } public byte Urg { get {return (byte)((BitField >> 2) & 1);} set {BitField = (ushort)(BitField & ~(1 } public byte Reserved2 { get {return (byte)(BitField & 3);} set {BitField = (ushort)((BitField & ~3) | value);} } } class Test { static void Main() { DIVERT_TCPHDR hdr = new DIVERT_TCPHDR(); hdr.BitField = 0x0F94; // 00001111 10010100 PrintBitFields(hdr); // make some changes hdr.HdrLength = 12; hdr.Fin = 0; hdr.Syn = 1; hdr.Rst = 1; hdr.Psh = 0; hdr.Ack = 1; hdr.Urg = 0; Console.WriteLine(
After changes values are now
); PrintBitFields(hdr); Console.ReadKey(); } static void PrintBitFields(DIVERT_TCPHDR hdr) { Console.WriteLine(HdrLength = {0} hdr.HdrLength); Console.WriteLine(Fin = {0} hdr.Fin); Console.WriteLine(Syn = {0} hdr.Syn); Console.WriteLine(Rst = {0} hdr.Rst); Console.WriteLine(Psh = {0} hdr.Psh); Console.WriteLine(Ack = {0} hdr.Ack); Console.WriteLine(Urg = {0} hdr.Urg); } } The output should be: HdrLength = 15 Fin = 1 Syn = 0 Rst = 0 Psh = 1 Ack = 0 Urg = 1 After changes values are now HdrLength = 12 Fin = 0 Syn = 1 Rst = 1 Psh = 0 Ack = 1 Urg = 0

shine pb · Answer

I think bit positions are not possible in c# structure. It is possible in c++. My question is how we can set bit position in c# structure.Is there any ways to do it in C#? For Example: typedef struct { UINT16 SrcPort:16; UINT16 DstPort:16; UINT32 SeqNum:32; UINT32 AckNum:16; UINT16 Reserved1:4; UINT16 HdrLength:4; }IP_HDR How can we create a structure like this in c# with bit positions?

Jignesh Trivedi · Answer

hi your question is not too much clear. you want to set array length from out side is it correct? you may take help from contructor. public struct myTest { public int[] b // Constructor: public myTest(int length) { b = new int[length]; } } hope this will help you.

Abhishek Jain · Answer

Try something like this: [global::System.AttributeUsage(AttributeTargets.Field AllowMultiple = false)] sealed class BitFieldLengthAttribute : Attribute { uint length; public BitFieldLengthAttribute(uint length) { this.length = length; } public uint Length { get { return length; } } } struct DIVERT_TCPHDR { UInt16 SrcPort; UInt16 DstPort; UInt32 SeqNum; UInt32 AckNum; [BitFieldLength(4)] UInt16 Reserved1; [BitFieldLength(4)] UInt16 HdrLength; [BitFieldLength(1)] UInt16 Fin; [BitFieldLength(1)] UInt16 Syn; [BitFieldLength(1)] UInt16 Rst; [BitFieldLength(1)] UInt16 Psh; [BitFieldLength(1)] UInt16 Ack; [BitFieldLength(1)] UInt16 Urg; [BitFieldLength(2)] UInt16 Reserved2; UInt16 Window; UInt16 Checksum; UInt16 UrgPtr; }; I have referred it from here: http://stackoverflow.com/questions/14464/bit-fields-in-c-sharp Regards AJ

Iftikar Hussain · Answer

Hi Not clear about your query. Can you explain bit more? You can declare structure in C#. Please refer the below link http://www.dotnetperls.com/struct Regards Iftikar