Reading and writing binary files using c#
Quite a bit has been written about reading structured binary data from or writing it to files see [1,2,3].
Now, if you wanted to accomplish the same with C A stream always requires a byte array as the target for read operations. Or if you use a BinaryReader the ReadBytes method returns a byte array. In any case the data read into a byte array needs to be copied into the target struct. PtrToStructure to do this, and  offers a much more elegant solution using an unsafe assignment like this:.
Alternatively you could read data from an input stream in little chunks using a BinaryReaderwhich would mean you deserialize the data into each field by hand. This avoids the extra copy of data, but requires much effort on your side. However, due to a customer engagement I recently started thinking about this. The approaches found in the literature, though, are too slow for him. I felt challenged by this problem. Look at the following code for reading the ID3v1 tag of a MP3 file:.
And no extra copies of data are needed. Well, I removed the premise that underlies the usual literature on this topic: IO to access the file, but the old CRT fxxx reading and writing binary files using c#. I just wrote a small unmanaged DLL wrapper around the basic stdio C functions like fopenfread etc. Look at my C function for reading data from a file:. This Read method you just need to pass the address of the target struct to receive the data from the file and the number of bytes to read.
No extra byteno explicit deserialization of fields. You just need to be willing to use unsafe reading and writing binary files using c#. Fast Binary File Reading with Reading and writing binary files using c#http: Read binary files more efficiently using Chttp: Unsafe and reading from fileshttp: Assuming this is C 2. Thx for your idea. However, it introduces the very data copy I wanted to avoid: Nonetheless using Generics could make my Read method a little easier, since the struct length could be determined automatically.
When you wanto to write the struct into a binary file, you must use a code like this: AllocHGlobal size ; Marshal. ToPointer ; while size--! FreeHGlobal handle ; binwriter. The Marshal class is declared in the System. Home About Sign In. PtrToStructure to do this, and  offers a much more elegant solution using an unsafe assignment like this: Look at the following code for reading the ID3v1 tag of a MP3 file: How is this done? Look at my C function for reading data from a file: You just need to be willing to use unsafe code: Resources  Anthony Baraff: Interop namespace Comments have been disabled for this content.