Using std::istream_iterator to read up to N values

Question

If I know for certain that my input stream contains 10 values, I can read them with

std::copy_n(std::istream_iterator(input), 10, output);
         


        

Answer 1

You could use copy_if and a counter - that unfortunately doesn't break early.

int count = 0;
std::copy_if(std::istream_iterator(input), std::istream_iterator(), output,
    [&]() { return ++count < 10; });

If you'd like to stick with algorithms (instead of plain for loop), I'd suggest you roll you own (I answered a similar question in the past.)