Re: [Dev-C++] doubt

[Abhijit S. <mu...@gm...>]

AFAIK, GCC (and derivatives) don't store structures linearly, they pad the
elements for optimization reasons. So if you want to read in stuff, you'll
have to read them in separately.

I think there's a command-line option somewhere to disable this behaviour...
Over to you, <put_your_name_here>.

--------------------------
http://mudeth.tripod.com

----- Original Message -----
From: "balamurali muraleedharan" <bal...@re...>
To: <dev...@li...>
Sent: Tuesday, June 11, 2002 7:25 PM
Subject: [Dev-C++] doubt



> int main()
> {
> bitmapfileheader bmpf;
> cout<<sizeof(bmpf);
> }
> here the result shows the size as 16bytes instead of 14bytes
> also while reading into this structure using file.open and
> file.read statement always wrong data is contained in the
> structure where the read data is stored.Why is this so?
> There is error only while reading into the structure as a whole as
> in the case
> file.open("file.bmp",ios::binary|ios::in);
> file.read((char*)&bmpf,sizeof(bmpf));
> This always reads erroneous values into the corresponding elements
> in the structure.But
> file.open("file.bmp",ios::binary|ios::in);
> file.read((char*)&bmpf.signature,sizeof(bmpf.signature));
> file.read((char*)&bmpf.filesize,sizeof(bmpf.filesize));
> file.read((char*)&bmpf.reserved,sizeof(bmpf.reserved));
> file.read((char*)&bmpf.dataoffset,sizeof(bmpf.dataoffset);
> this reads the correct values into the respective elements of the
> structure.
> why is this so?
> why cant we simply read the contents of the file into the
> structure using the first statement?what really happens during
> this process?
> I am using G++ in Linux environment.
> Please help me.