Not able to read whole file - c++

Question

I'm making a C++ program to be able to open a .bmp image and then being able to put it in a 2D array. Right now i have the code like this:
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
#include "Image.h"
using namespace std;
struct colour{
int red;
int green;
int blue;
};
Image::Image(string location){
fstream stream;
string tempStr;
stringstream strstr;
stream.open(location);
string completeStr;
while(!stream.eof()){
getline(stream, tempStr);
completeStr.append(tempStr);
}
cout << endl << completeStr;
Image::length = completeStr[0x13]*256 + completeStr[0x12];
Image::width = completeStr[0x17]*256 + completeStr[0x16];
cout << Image::length;
cout << Image::width;
cout << completeStr.length();
int hexInt;
int x = 0x36;
while(x < completeStr.length()){
strstr << noskipws << completeStr[x];
cout << x << ": ";
hexInt = strstr.get();
cout << hex << hexInt << " ";
if((x + 1)%3 == 0){
cout << endl;
}
x++;
}
}
Now if i run this on my test file of 256x256 it will print fine, until it reaches 0x36E where it gives an error / doesn't go further. This happens because the completeStr string doesn't recieve all the data that is in the bmp file. Why isn't able to read all the lines in the bmp file?

Answer 1

There are a number of problems with your code. The principal
one (and probably the reason for your problem) is that you are
opening the file in text mode. Technically, this means that if
the file contains anything but printable characters and a few
specific control characters (like '\t'), you have undefined
behavior. In practice, under Windows, this means that sequences
of 0x0D, 0x0A will be converted into a single '\n', and that
a 0x1A will be interpreted as the end of the file. Not really
what one wants when reading binary data. You should open the
stream in binary mode (std::ios_base::binary).
Not a serious error, but you shouldn't really use an fstream
if you are only going to read the file. In fact, using an
fstream should be very rare: you should use either ifstream
or ofstream. The same thing holds for stringstream (but
I don't see any role for stringstream when reading a binary
file).
Also (and this is a real error), you are using the results of
getline without checking whether is succeeded. The usual
idiom for reading lines would be:
while ( std::getline( source, ling ) ) ...
But like stringstream, you don't want to use getline on
a binary stream; it will remove all of the '\n' (which have
already been mapped from CRLF).
If you want all of the data in memory, the simplest solution is
something like:
std::ifstream source( location.c_str(), std::ios_base::binary );
if ( !source.is_open() ) {
// error handling...
}
std::vector<char> image( (std::istreambuf_iterator<char>( source ) ),
(std::istreambuf_iterator<char>()) );

Answer 2

std::getline reads in a line of text.
It's not useful for a binary file.
Open the file in binary mode and use unformatted input operations (like read).