Question

can you use Insert Iterators while reading from a file to put the data into STL container?

for example:

FILE *stream;
fread(back_inserter(std::list), sizeof(int), 1, stream);

Answer 1

C++ streams are not compatible with C stdio streams. In other words, you can’t use C++ iterators with FILE* or fread. However, if you use the C++ std::fstream facilities along with istream_iterator, you can use an insertion iterator to insert into a C++ container.

Assuming you have an input file “input.txt” which contains ASCII text numbers separated by whitespace, you can do:

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

int main()
{
 std::ifstream ifs("input.txt");
 std::vector<int> vec;
    // read in the numbers from disk
 std::copy(std::istream_iterator<int>(ifs), std::istream_iterator<int>(), std::back_inserter(vec));
    // now output the integers
 std::copy(vec.begin(), vec.end(), std::ostream_iterator<int>(std::cout, "\n"));
}