Error with code (working with text files)

[kyiro37]

Okay, sorry if this is considered a duplicate but it is a different problem with the same code discussed in another thread.

I have two problems:

1. my test file is only 7 lines. When I run my code, not all of the lines are outputted into the other text file like they should be. Some are, in a random order (which is correct). It varies between 1 and 6 out of 7 lines so far. I cannot figure out the problem.

2. I want my program to run through a loop; read from one file, randomize it and output it into another file; next pass, read from the 2nd file and randomize again and input back into the first file (rinse and repeat).
I tried using flush(); but it was not working properly.

If anyone can help with either problem I would be very appreciative. To be honest, most of this code is over my head, but I'm trying to understand it.

  #include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include <ctime>
#include <cstdlib>
#include <algorithm>

using namespace std;


std::vector<std::streamoff> get_offsets( std::istream& file )
{  
    std::vector<std::streamoff> offsets( 1, 0 ) ;

    file >> std::noskipws ;
    std::streamoff pos = 0 ;
    char c ;
    while( file >> c )
    {
        pos = pos + 1 ;
        if( c == '\n' ) offsets.push_back(pos) ;
    }

    file.clear() ;
    return offsets ;
}

void write( std::istream& in, std::ostream& out,
            const std::vector<std::streamoff>& offsets )
{
    for( std::size_t i = 0 ; i < offsets.size() ; ++i )
    {
        in.seekg( offsets[i] ) ;
        std::string line ;
		if( std::getline( in, line ) && !line.empty() ) out << line;
    }
}

int main()
{
    std::ifstream file1("Text1.txt", std::ios::binary ) ;
	std::ofstream file2("Text2.txt");
    std::vector<std::streamoff> offsets = get_offsets(file1) ;

    std::srand( (unsigned)time(0) ) ;
    std::random_shuffle( offsets.begin(), offsets.end() ) ;
    write( file1, file2, offsets ) ;

	
	return(0);
}

That is all of the code. Here is my code to run the loop:

int zq=0;
for (zq=0; zq<=4; zq++)
{
if (zq%2==0)
{
std::ifstream file1("Text1.txt", std::ios::binary ) ;
	std::ofstream file2("Text2.txt");
    std::vector<std::streamoff> offsets = get_offsets(file1) ;

    std::srand( (unsigned)time(0) ) ;
    std::random_shuffle( offsets.begin(), offsets.end() ) ;
    write( file1, file2, offsets ) ;
}
else
{
std::ifstream file1("Text2.txt", std::ios::binary ) ;
	std::ofstream file2("Text1.txt");
    std::vector<std::streamoff> offsets = get_offsets(file1) ;

    std::srand( (unsigned)time(0) ) ;
    std::random_shuffle( offsets.begin(), offsets.end() ) ;
    write( file1, file2, offsets ) ;
}
}

I excluded my use of flush; because it wasn't working. I read up on it and thought I used it the same as the example but it had an error.

*And by "my" code, I actually mean "someone wrote this code for me and I am trying to wrap my head around it and make it do exactly what I want. :)".

[cire]

I think the fact that you're opening file1 in binary mode and using the extraction operator and getline on it might be an issue.

Changing get_offsets to:

std::vector<std::streamoff> get_offsets( std::istream& file )
{  
    std::vector<std::streamoff> offsets( 1, file.tellg() ) ;

    const std::streamoff eof = std::char_traits<std::istream::char_type>::eof() ;

    std::string line ;
    while ( std::getline(file, line) && file.peek() != eof )
        offsets.push_back(file.tellg()) ;

    file.clear() ;
    return offsets ;
}

and changing line 42 to std::ifstream file1("Text1.txt") ; worked for me.

[kyiro37]

Well, that totally fixed my problem with having extra lines inputted and not all of the text being inputted.

Thanks a bunch!

I will still continue trying to fix my loop and using flush; but if anyone has any input it would be appreciated!!

Although I feel pretty bad because this whole program has been written by someone else and now that updated function... with me changing very few things... -__-

Sorry. :(

Anyway, thanks everyone and anyone.

UPDATE:

Well, I updated my code to add in what you suggested and it seems to have fixed both of my problems. When adding in the loop, it seems like it is doing what I want. (I am not sure how to test it, but changing it from 100 to 1000 times increases the amount of time the program takes to finish, so I assume that it is working.)


Thank you very much!