Reuse of the stream iterators

Question

I have a file that need to be open multiple times during the runtime. Each time some text are appendedd into the file. Here is the code:

    ofstream fs;
    fs.open(debugfile, fstream::app);
    ostream_iterator<double> output(fs, " ");
    copy(starting_point.begin(), starting_point.end(), output);
    ...
    fs.open(debugfile, fstream::app);
    ostream_iterator<double> output1(fs, " ");
    copy(starting_point.begin(), starting_point.end(), output1);

My question is can I use one stream iterator "output" every time I open the file, e.g. some way to clean it?

Thanks

Why not put the reusable code in a function and call the function multiple times? — NathanOliver, Aug 04 '16 at 14:27

score 1 · Answer 1 · answered Aug 04 '16 at 14:30

You may use the following code:

ofstream fs;
fs.open(debugfile, fstream::app);
ostream_iterator<double> output(fs, " ");
copy(starting_point.begin(), starting_point.end(), output);
...
fs.open(debugfile, fstream::app);
output = ostream_iterator<double>(fs, " ");
copy(starting_point.begin(), starting_point.end(), output1);

Here the same variable output is used to store the iterator, but the iterator itself is created from scratch and assigned to this variable using operator =.

score 0 · Answer 2 · edited May 23 '17 at 11:44

0

For me, there is nothing to do (appart reassign value) for your problem.

Just don't forget to close and clear your stream before re-open it :

std::ofstream file("1");
// ...
file.close();
file.clear(); // clear flags
file.open("2");

from : C++ can I reuse fstream to open and write multiple files?

edited May 23 '17 at 11:44

Community

1
1

answered Aug 04 '16 at 14:32

baddger964

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This does not answer the question about the iterator. – Jonathan Mee Aug 04 '16 at 14:32

Reuse of the stream iterators

2 Answers2