Thread: iFstream_iterator???

ok, there is an istream_iterator like istream_iterator<int>(cin). what i need is an ifstream_iterator for a file like istream_iterator<int>(datafile). my code works when cin is used, however failes when i try to use a datafile. if anybody knows of a nifty trick to convert a class std::basic_ifstream<char,struct std::char_traits<char> to a class std::basic_istream<char,struct std::char_traits<char> >, so i can use a istream_iterator with a converted ifstream object, or an ifstream iterator (i checked and didnt see one) im very interested in hearing about it. thanks.

Works for me like this

Code:

#include <iostream>
#include <fstream>
#include <iterator>

using namespace std;

int main()
{
    ifstream ifs("in.txt");
    istream_iterator<char> ii(ifs);
    
    while (ifs)
        cout<< *ii++;
}

An ifstream is an istream, so you shouldn't be having any problems unless you're doing it wrong.

#include <iterator>
#include <vector>
#include <iostream>
#include <fstream>
int main()
{
string filename = "test.txt";
std::ifstream datafile;
datafile.open(filename.c_str());
vector<int> bobs;
copy( (istream_iterator<int> (datafile)),istream_iterator<int>(),back_inserter( bobs));
return 0;
}

The vector bobs is left empty after this code executes. This is a scaled down example of how im trying to load the data.

Code:

#include <iterator>
#include <vector>
#include <iostream>
#include <fstream>
#include <algorithm>

using namespace std;

int main()
{
    ifstream datafile("test.txt");
    vector<int> bobs;

    copy(istream_iterator<int>(datafile),istream_iterator<int>(),back_inserter(bobs));
    copy(bobs.begin(), bobs.end(), ostream_iterator<int>(cout, " "));

    return 0;
}

I'm really not having any problems with it. What compiler do you use? Perhaps the stream iterators aren't well written on your compiler, mine is Visual C++ 6.0.

MSFT VC++ 6.0 on win2k. Its been having trouble with iterators all day. im starting to think its time for a reinstall. Seems like code that works fine with others doesnt work with mine. I dont believe i added or removed any libs recently. this is odd.