Reading a file into a binary array in c++

Question

I have got a file that contains data for multiple jpegs (along with some garbage), i need to extract binary from this file, filter out the garbage and create jpegs. I know the starting binary sequence of the jpegs.

char buffer[30];
ifstream fin;
fin.open ("FILENAME.raw", ios::in | ios::binary);
while (!fin.eof())
{
    fin.read(buffer,30);
    cout<<buffer[2]<<endl;
}
fin.close();

Here i am trying to print the file in binary but, when i run this code, alien characters are printed on the screen.

Probably you have alien characters in your file. That's usually the case with binary data. — john
– john, Commented Oct 23, 2012 at 6:38
Seems everything's fine and you have no problem. And in fact you didn't ask a question. — Zane
– Zane, Commented Oct 23, 2012 at 6:42

Kadir Erdem Demir · Accepted Answer · 2012-10-23 08:58:41Z

2

I think problem here was "cout << buffer[2]" which was converting your binary information to charecters. Try int cast before , also you should use a static "unsigned char array" because binary data can be unsigned .That will work :

unsigned char buffer[ 30 ];
ifstream fin;
fin.open ("FILENAME.raw", ios::in | ios::binary);
while (!fin.eof())
{

    fin.read( (char*)( &buffer[0] ), 30 ) ;
    cout << (int)buffer[2] << " ";
}
fin.close();
return 0;

Also if you want to traverse the binary why you are just printing buffer[2].

answered Oct 23, 2012 at 8:58

Kadir Erdem Demir

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Comments

LAP · Accepted Answer · 2012-10-23 08:37:46Z

1

You should double check the binary contents of the file, as your code seems perfectly fine.

answered Oct 23, 2012 at 8:37

LAP

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