Read data into structs?

Question

I would like to use the System.IO class to read binary data directly into some c# structs. But I dont see a way to do it. All the readers that I know of ( BinaryReader StreamReader) want a byte[] or char[] as the target buffer. I dont see a way to cast my struct into a byte[] so I can use these read methods. Does anyone have a solution for this? Thanks in advance.

bilnaad · Answer

Hmmm For a little test I developed a dll that has a StructReader and StructWriter derived from BinaryReader and BinaryWriter. The most efficient way of reading and writing struct is using the Marshal class. Like you said I used the Marshal to get the Size of the type. declare a byte[] and allocate unmanaged memory. Write the byte[] to that memory. And use PtrToStructure(). And the reverse for reading them back

bilnaad · Answer

btw this is only possible when the field of the struct contain no reference types. if you have a field of type string this code won't work. it works when fields are of type intuintlong etc...

bilnaad · Answer

It can be done very easy through pointers. This is what needed to convert a byte[] to a strcuture of your type. Structure structure; fixed( byte* ptr = data ) { structure = *((Structure*)ptr); } return structure; As you can see an pointer as created to byte[]. With this pointer you can cast the entire array to your Structure and store the value. it's very important to watch the size of byte[]. If the byte[] length is not equal to sizeof(Structure) then it can't be that struct. sizeof() return an int wich represents the size of your type. The type is measured by the typesizes of all variables wich are at struct scope.

franny · Answer

I think I now see how this is done. It seems a bit obtuse but here goes. Using BinaryRead() read the data from a source into a byte[] array. Then using Interopservices allocate unmanged memory the size of the structure. Marshal the byte array to the unmanaged memory by using Marsal.Copy. Then use PtrToStructure() to create a managed object from the unmanaged memory. Surely there is anohter way..... trinitron