stream does not append new line character

Question

I call the function write in a loop. I need to append several lines.

I pass

std::fstream file(filename);

to

write(info, &file);

The following code doesn't append new line character, or at least Notepad++ does not display it.(i get just a whitespace) :

void IO::write(const std::string& name, std::iostream* stream)
{
    (*stream) << "usr" << name << " === " << "\n";
}

What is wrong? How to append the new line to the text file?

Answer 1

To elaborate on my rather harsh comment, there is nothing wrong with your newline, but...

...use the correct types...

#include <iostream>
#include <fstream>

// ...
std::ofstream file( filename );
// ...

...and if you want to print info to the stream, just do it instead of going through some function...

// ...
file << "usr" << info << " === " << "\n";
// ...

...if you really want to make it a function, at least use references and the proper types...

void IO::write( std::ostream & stream, const std::string & name )
{
    stream << "usr" << name << " === \n";
}

// ...
IO::write( file, info );
// ...

...but the "traditional" way of doing output in C++ is to overload the operator<< for the class in question, and have the implementation for printing an instance sit right alongside the class member implementations instead of going through C-style functions...

class MyClass
{
    // ...
    friend std::ostream & operator<<( std::ostream & stream, const MyClass & obj );
    // ...
};

std::ostream & operator<<( std::ostream & stream, const MyClass & obj )
{
    stream << "usr" << obj.name << " ===\n";
    return stream;
}

// ...
MyClass mine;
file << "Hello\n" << mine << 42 << "\n";

Answer 2

I would also recommend that you use std::endl rather than "\n". std::endl flushs the file, "\n" does not.

After file is flushed (std::endl used or file closed). Try different editors to be sure, but end of line should be visible.

Jean