reading non-text file in c++ - c++

Question

I open the mp3 file by mistake with notepad++ ( Open with ) and show the entire file in text inside the notepad it was so cool.
since I am learning c++ again, I told myself let write a program that opens any file inside the console and display their content on the console so I begin my code like this :
int readAndWrite() {
string filename(R"(path\to\a\file)");
ifstream file(filename);
string line;
if (!file.is_open()) {
cerr << "Could not open the file - '"
<< filename << "'" << endl;
return EXIT_FAILURE;
}
while (getline(file, line)){
cout << line;
}
return EXIT_SUCCESS;
}
but it only shows 3 or 4 lines of the file and then exits the program I check my notepad++ again and find out about 700,000 line is in there.
I told myself maybe there is a character inside the file so I start writing the above code with the below changes. instead of displaying the file let's wrote inside a text file.
int readAndWrite() {
string filename(R"(path\to\a\file)");
string filename2(R"(path\to\a\file\copy)");
ifstream file(filename);
ofstream copy(filename2);
string line;
if (!file.is_open()) {
cerr << "Could not open the file - '"
<< filename << "'" << endl;
return EXIT_FAILURE;
}
while (getline(file, line)){
copy << line;
}
return EXIT_SUCCESS;
}
and again the same results. next try I give up on reading the file line by line so I start copying with this function.
void copyStringNewFile(ifstream& file, ofstream& copy)
{
copy << file.rdbuf();
}
and their results did not change a bit.
At this point, I told myself the problem is from file maybe and it is kinda is because when I use a simple text file all of the above codes work.

Answer 1

Like all other non-text files, mp3 files don't contain lines so you shouldn't use std::getline. Use istream::read and ostream::write. You can use istream::gcount to check how many characters that was actually read.
Since you are dealing with non-text files, also open the files in binary mode.
You should also test if opening both files works - that is, both the input and the output file.
Example:
#include <cerrno>
#include <cstring>
#include <fstream>
#include <iostream>
int readAndWrite() {
std::string filename(R"(path\to\a\file)");
std::string filename2(R"(path\to\a\file_copy)");
std::ifstream file(filename, std::ios::binary);
if(!file) {
std::cerr << '\'' << filename << "': " << std::strerror(errno) << '\n';
return EXIT_FAILURE;
}
std::ofstream copy(filename2, std::ios::binary);
if(!copy) {
std::cerr << '\'' << filename2 << "': " << std::strerror(errno) << '\n';
return EXIT_FAILURE;
}
char buf[1024];
while(file) {
file.read(buf, sizeof(buf));
// write as many characters as was read above
if(!copy.write(buf, file.gcount())) {
// write failed, perhaps filesystem is full?
std::cerr << '\'' << filename2 << "': " << std::strerror(errno) << '\n';
return EXIT_FAILURE;
}
}
return EXIT_SUCCESS;
}
int main() {
return readAndWrite();
}