Read byte from JPEG file??

[materithe]

Please advise me how to read the JPEG file into byte array. I was trying to use ifstream and ios::binary as following:

#include <fstream>
#include <iostream>

using namespace std;

int main()
{
ifstream myFile;
myFile.open("butterfly.jpeg", ios::in | ios::binary);

//not the end of file
while(!myFile.eof())
{
int line;
myFile >> line;
cout << line << endl;
}
}

Though, what I got was infinitive print of "4" like this:
4
4
4
4
...

Thank you.

[Galik]

What are you expecting outputting JPEG data to the console to achieve?

[Galik]

materithe wrote:

Please advise me how to read the JPEG file into byte array

You could use something like this:

#include <string>
#include <fstream>
#include <sstream>

int main()
{
    std::ifstream ifs("butterfly.jpeg", ios::in | ios::binary); // input file
    std::ostringstream oss; // output to string

    int len;
    char buf[1024];
    while((len = ifs.readsome(buf, 1024)) > 0)
    {
        oss.write(buf, len);
    }

    std::string data = oss.str(); // get string data out of stream
}

[materithe]

Thanks,

I will try this right now. What I have to do is to write a JPEG decoder (taking in a JPEG file and produce a BMP file).

So right now, I try to get the file into stream of bytes and apply reverse compression algorithms.

Thank you. If you have any more advise for me, please let me know.

[materithe]

Dear Galik,

I get compiling error with your code for line 7 as it says:

Multiple markers at this line
- unused variable 'in'
- unused variable 'binary'
- `ios' has not been declared
- `in' was not declared in this
scope
- `binary' was not declared in
this scope

I am using Eclipse IDE with MinGW compiler.

Thank you.

[Galik]

This should work:
std::ifstream ifs("butterfly.jpeg", std::ios::in | std::ios::binary);

Why don't you use a jpeg library for this?

http://www.ijg.org/