How to write a struct to a file?

  • Thread starter Thread starter Dae-Suk Chung
  • Start date Start date
D

Dae-Suk Chung

Hi,
What is the easiest way to write a struct(with biary data) to a file ?
do I need to covert it through e.g. Marshal class ?


Thanks for any tips!

DaeSuk.
 
I think this will do it:


byte [] buff = null;
unsafe
{
buff = new byte [sizeof(MyStruct)];
}
IntPtr ptr = Marshal.AllocHGlobal(buff.Length);
Marshal.StructureToPtr(myStruct, ptr, true);
Marshal.Copy(ptr, buff, 0x0, buff.Length);
Marshal.FreeHGlobal(ptr);
FileStream fs = new FileStream("C:\\MyStruct.bin", FileMode.Create,
FileAccess.Write, FileShare.None);
fs.Write(buff, 0x0, buff.Length);
fs.Close();
 
Dennis,

While this might do it, if the structure contains pointers, it is not
going to accurately write the structure, as it won't know how to dereference
the pointer information. Also, this assumes that the structure can be
marshaled correctly across the managed/unmanaged boundary (which is also
more expensive).

I would recommend appending the Serializable attribute to the structure,
and then passing the structure to a BinaryFormatter (for a compact, fast,
format) or a SoapFormatter (for an XML document), and use that.

If your structure isn't complex, you could even use the XmlSerializer.

Hope this helps.


--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

Dennis Myrén said:
I think this will do it:


byte [] buff = null;
unsafe
{
buff = new byte [sizeof(MyStruct)];
}
IntPtr ptr = Marshal.AllocHGlobal(buff.Length);
Marshal.StructureToPtr(myStruct, ptr, true);
Marshal.Copy(ptr, buff, 0x0, buff.Length);
Marshal.FreeHGlobal(ptr);
FileStream fs = new FileStream("C:\\MyStruct.bin", FileMode.Create,
FileAccess.Write, FileShare.None);
fs.Write(buff, 0x0, buff.Length);
fs.Close();




Dae-Suk Chung said:
Hi,
What is the easiest way to write a struct(with biary data) to a file ?
do I need to covert it through e.g. Marshal class ?


Thanks for any tips!

DaeSuk.
Click to expand...
Click to expand...
 
I see, thanks,
one more question then,
what I want to do is to be able to write the structs to a file, ie. append
but also to position myself using seek and update a record.
can I achieve this using a serializable struct and BinaryFormatter ?
if not, the first option using the unsafe codes seems to be the only option
?


Thanks again for any advice!
DaeSuk.





Nicholas Paldino said:
Dennis,

While this might do it, if the structure contains pointers, it is not
going to accurately write the structure, as it won't know how to dereference
the pointer information. Also, this assumes that the structure can be
marshaled correctly across the managed/unmanaged boundary (which is also
more expensive).

I would recommend appending the Serializable attribute to the structure,
and then passing the structure to a BinaryFormatter (for a compact, fast,
format) or a SoapFormatter (for an XML document), and use that.

If your structure isn't complex, you could even use the XmlSerializer.

Hope this helps.


--
- Nicholas Paldino [.NET/C# MVP]
- (e-mail address removed)

Dennis Myr? said:
I think this will do it:


byte [] buff = null;
unsafe
{
buff = new byte [sizeof(MyStruct)];
}
IntPtr ptr = Marshal.AllocHGlobal(buff.Length);
Marshal.StructureToPtr(myStruct, ptr, true);
Marshal.Copy(ptr, buff, 0x0, buff.Length);
Marshal.FreeHGlobal(ptr);
FileStream fs = new FileStream("C:\\MyStruct.bin", FileMode.Create,
FileAccess.Write, FileShare.None);
fs.Write(buff, 0x0, buff.Length);
fs.Close();




Dae-Suk Chung said:
Hi,
What is the easiest way to write a struct(with biary data) to a file ?
do I need to covert it through e.g. Marshal class ?


Thanks for any tips!

DaeSuk.
Click to expand...
Click to expand...
Click to expand...
 
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