CODEWITHSUNDEEP
c++
Shengye Jin
Shengye Jin

Reputation: 35

How to use ostream_iterator<> to output result to a newfile?

I am a fresh about C++, I have met an issue, I want to use the following codes (from Cplusplus ) but to output my result to a new file or use a vector to keep it(i prefer to use a vector), what should I do? Thanks!

// ostream_iterator example
#include <iostream>     // std::cout
#include <iterator>     // std::ostream_iterator
#include <vector>       // std::vector
#include <algorithm>    // std::copy

int main () {
  std::vector<int> myvector;
  for (int i=1; i<10; ++i) myvector.push_back(i*10);

  std::ostream_iterator<int> out_it (std::cout,", ");
  std::copy ( myvector.begin(), myvector.end(), out_it );
  return 0;
}

Upvotes: 2

Views: 4986

Answers (1)

R Sahu
R Sahu

Reputation: 206707

You can use a std::ofstream in place of std::cout.

Here's your code modified to write the output to a file.

// ostream_iterator example
#include <iostream>     // std::cout
#include <iterator>     // std::ostream_iterator
#include <vector>       // std::vector
#include <algorithm>    // std::copy
#include <fstream>      // std::ofstream

int main () {
  std::vector<int> myvector;
  for (int i=1; i<10; ++i) myvector.push_back(i*10);

  std::ofstream of("myoutput.txt");

  std::ostream_iterator<int> out_it (of,", ");
  std::copy ( myvector.begin(), myvector.end(), out_it );
  return 0;
}

To copy the output to a vector, use a back_inserter.

std::vector<int> foo;
std::copy (myvector.begin(), myvector.end(), std::back_inserter(foo));

You can also make direct copy:

std::vector<int> foo = myvector;

Upvotes: 5

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