Manage File : c++

#include <string>
#include <iostream>
#include <fstream>


std::string memoryData(std::ifstream &file, int startAt, int stopAt, bool show = false)
{
    std::string data;

    int memorySize = stopAt - startAt;

    file.seekg(startAt);
    data.resize(memorySize);
    file.read(&data[0], memorySize);

    if (show)
        std::cout << data;

    return data;
}

std::string memoryData(std::fstream &file, int startAt, int stopAt, bool show = false)
{
    std::string data;

    int memorySize = stopAt - startAt;

    file.seekg(startAt);
    data.resize(memorySize);
    file.read(&data[0], memorySize);

    if (show)
        std::cout << data;

    return data;

}

std::ifstream::pos_type fileSize(const char* filename)
{
    std::ifstream in(filename, std::ifstream::ate | std::ifstream::binary);
    return in.tellg();
}


int main()
{

    std::ifstream readA("myanimation.json", std::ios::in | std::ios::binary);
    std::ifstream readB("myanimation.png", std::ios::in | std::ios::binary);

    std::ofstream writeAB("myanimation.mas", std::ios::out | std::ios::binary);

    writeAB << readA.rdbuf() << "[END_OF_JSON]" << readB.rdbuf() << "[END_OF_PNG]";

    readA.close();
    readB.close();
    writeAB.close();

    std::ifstream readMAS("myanimation.mas", std::ios::in | std::ios::binary);

    std::ofstream writeJSON("myanimationClone.json", std::ios::out | std::ios::binary);
    std::ofstream writePNG("myanimationClone.png", std::ios::out | std::ios::binary);

    std::string memoryPNG;
    std::string memoryJSON;

    if (readMAS.is_open())
    {
        writeJSON << memoryData(readMAS, 0, 276);
        writePNG << memoryData(readMAS, 289, 30908);
    }

    readMAS.close();

    writeJSON.close();
    writePNG.close();


    //std::ifstream fileTEST("myanimationClone.json", std::ios::in | std::ios::binary);

    std::fstream fileTEST("test.txt", std::ios::in | std::ios::out | std::ios::binary);

    std::string endOfJSON = "<END_OF_JSON>";

    int pos = 0;
    int sizeFile = 0;

    if (fileTEST.is_open())
    {

        // Write in file !
        fileTEST << "I am" << std::endl;
        fileTEST << "a JSON file" << "\n";
        fileTEST << "who contain" << "\n";
        fileTEST << "Good" << "\n";
        fileTEST << "Animation" << "\n";
        fileTEST << endOfJSON+"\n";
        fileTEST << "here is the PNG DATA\n";
        fileTEST << "here is the PNG DATA\n";
        fileTEST << "here is the PNG DATA\n";
        fileTEST << "here is the PNG DATA\n";


        // Read in file
        std::string line;

        fileTEST.seekg(0);


        while (std::getline(fileTEST, line))
        {
            //std::cout << "Position : " << fileTEST.tellg() << "\n";
            std::cout << line << "\n";
            //std::cout << "Position : " << fileTEST.tellg() << "\n";
        }

        fileTEST.clear();

        fileTEST.seekg(0, fileTEST.beg);

        //std::cout << "Position : " <<fileTEST.tellg() << "\n";
        sizeFile = fileSize("test.txt");
        std::cout << "fileSize = " << sizeFile;

        while (fileTEST.good())
        {
            std::getline(fileTEST, line);

            //std::cout << line;

            if (line.find("<END_OF_JSON>") != std::string::npos)
            {
                pos = fileTEST.tellg() - (endOfJSON.length()+1);
                std::cout << "--- Found at "<< pos <<"\n";
            }

//           char ch;
//           fileTEST.get(ch);
//           std::cout << ch;
        }

        fileTEST.clear();

        std::ofstream fileJSON("json.txt", std::ios::out | std::ios::binary);
        std::ofstream filePNG("png.txt", std::ios::out | std::ios::binary);

        if (fileJSON.is_open())
        {
            fileJSON << memoryData(fileTEST, 0, pos);
            fileJSON.close();
        }
        else
            std::cout << "- fileJSON error !\n";


        if (filePNG.is_open())
        {
            filePNG << memoryData(fileTEST, pos+(endOfJSON.length()+1), sizeFile);
            filePNG.close();
        }
        else
            std::cout << "- filePNG error !\n";

    }

    fileTEST.close();

    std::cout << "\n";
    std::cout << "- Operation OK ! \n";
    return 0;
}