Problem of read file in C++

I have .raw files which is generated by Photoshop.

And I now want to read the values in .raw files to my C++ program and then
do some calculation on it.

Then I would like to ask two things. What is the data structure of a .raw file?
(RGB? A 2D array or whatever?)
And can anybody please give me some brief idea on how to read the file content?

Like what?

How to read binary files - fopen("file.raw", "rb" );

How to interpret all the bytes?
Maybe here - http://www.wotsit.org/

Maybe type "photoshop raw file format" into a search engine.

Maybe create something simple, like a 16x16 image containing 3 primary colour squares, say 8x8 (a bit like the MS logo) and save that in RAW format.
Then look at that file using a hex editor.
Make very small changes and match that to changes in the file.

I used the following code to read a raw file:

Code:

const int size = 1080*1080;
int r;
	
unsigned char*  A;
A = (unsigned char*)malloc(size*sizeof(char));

fin.open("test.raw",ios::binary);	// read data file of four integers
for(r=0; r<size; r++)	// into array
fin >> A[r];
fin.close();	
	
ofstream fout;
fout.open("result.raw",ios::binary);
// write data file
for(r=0; r<size; r++){	
	fout << A[r];
}

fout.close();

So, this is just a roundtrip that import the raw file into the array A, and then export data into the file result.raw. However, the image output is incomplete. What's the problem with my coding?

You're using formatted I/O (the >> operator) for binary data. That's the most obvious problem. With binary data, use read() and write().