How to copy large text files?

[airman9519]

I have a problem. I need to find a way to copy from one text file to another FAST!
Let's say for example a file is 50 MB and I need to copy it within about 3 seconds.

#include <iostream>
#include <fstream>

using namespace std;

int main()
{
    ifstream ifstr("pi.txt");
    ofstream ofstr("pi2.txt");
    char x[1000000];
    int y;
    
    if(!ifstr.is_open || !ofstr.is_open)
    {
    cout << "Error!\n";
    system("pause");
    return 0;
}
    while(!ifstr.eof())
    {
    for (y = 0;y < 1000000;y++)
    {
       ifstr >> x[y];
        }
        for (y = 0;y < 1000000;y++)
        {
            ofstr << x[y];
            }}
            
    
    ifstr.close();
    ofstr.close();
    cout << "Done!\n";
    system("pause");
    return 0;
    }

This code just doesn't work! It's too slow!
If anyone has any ideas please help!

[Bazzy]

You should get unformatted input when copying files
something like ofstr.put ( ifstr.get() ); will copy one character at the time

[airman9519]

Thanks man it definitely is faster but if anyone has any other ideas i'll try them

[Bazzy]

You could copy chunks of the file using write and read
http://www.cplusplus.com/reference/iostream/ostream/write/

[Galik]

You could try this:

#include <fstream>

const size_t BUF_SIZE = 8192;

void copy(std::istream& is, std::ostream& os)
{
	size_t len;
	char buf[BUF_SIZE];

	while((len = is.readsome(buf, BUF_SIZE)) > 0)
	{
		os.write(buf, len);
	}
}

int main()
{
	std::ifstream ifs("input.txt");
	std::ofstream ofs("output.txt");

	copy(ifs, ofs);
}

[sargon94]

you could also use the WinAPI function CopyFile (): http://msdn.microsoft.com/en-us/library/e1wf9e7w(VS.85).aspx

[airman9519]

Thanks you guys are awesome but because I have only recently started working in c++ I decided to use CopyFile() because it's very simple yet very fast