C++ getline() slower than Java's readLine()

I'm trying to read a 250K line file, and apply regex to each of these lines. However the code is much much slower than Java's readline function. In Java all the parsing is done in ~10 sec, while in C++ it takes more than 2 mins. I've seen the relative C++ ifstream.getline() significantly slower than Java's BufferedReader.readLine()? and added these two lines on top of main:

std::ifstream::sync_with_stdio(false);
std::ios::sync_with_stdio(false);

The rest of the code (I simplified it to remove any delays regex might be causing):

#include "stdafx.h"
#include 

#include 
#include 
#include 


int _tmain(int argc, _TCHAR* argv[])
{

    std::string libraryFile = "H:\\library.txt";
    std::ios::sync_with_stdio(false);

    std::string line;

    int i = 1;

    std::ifstream file(libraryFile);
    while (std::getline (file, line)) {
        std::cout << "\rStored " << i++ << " lines.";
    }

    return 0;

}

The example seems quite simple, but even the fix suggested in most posts doesn't seem to work. I've run the .exe multiple times using release settings in VS2012, but I just can't reach Java's times.

Answer

The slowness is caused by a couple of things.

• Mixing cout and cin: The C++ IO library has to synchronize cout every time cin is used. This is to ensure things like input prompts are displayed before asking for input. This really hurts buffering.




• Using the Windows console output: The Windows console is so slow, especially while doing terminal emulation, that it isn't funny. If at all possible output to a file instead.