Re: reading from a file
On Oct 9, 12:18 am, Joshua Maurice <joshuamaur...@gmail.com> wrote:
On Oct 7, 3:38 pm, suresh <suresh.amritap...@gmail.com> wrote:
I wrote a code like this and it failed to read from file. My
question what is the shortest code to read from a file and
populate a vector?
vector<double> d;
ifstream in("myfile.txt");
copy(in.begin(),in.end(),back_inserter(d));
For starters, your code does not compile. Please see the FAQ on how to
posthttp://www.parashift.com/c++-faq-lite/
Specifically please post complete compile-able examples. If you do not
know enough to post a complete compilable example, then do the closest
that you can. In the process of trying to make it compile (and work),
you might learn it on your own.
ifstream has no member functions begin and
end.http://cplusplus.com/reference/iostream/ifstream/
If you want to treat a std::istream as a readable sequence ala
iterators, see std::istream_iterator.http://cplusplus.com/reference/std/iterator/istream_iterator/
A complete example would be:
#include <algorithm>
#include <fstream>
#include <functional>
You don't use this one:-).
#include <iterator>
#include <vector>
using namespace std;
int main()
{
vector<double> d;
ifstream in("myfile.txt");
copy(
istream_iterator<double>(in),
istream_iterator<double>(),
back_inserter(d)
);
}
You can do even better using the two iterator constructor of
vector:
std::istream in( "myfile.txt" );
std::vector<double> d(
(std::istream_iterator<double>( in )),
(std::istream_iterator<double>()));
--
James Kanze