Splitting std::string and inserting into a std::set

Question

As per request of the fantastic fellas over at the C++ chat lounge, what is a good way to break down a file (which in my case contains a string with roughly 100 lines, and about 10 words in each line) and insert all these words into a std::set?

Answer 1

The easiest way to construct any container from a source that holds a series of that element, is to use the constructor that takes a pair of iterators. Use istream_iterator to iterate over a stream.

#include <set>
#include <iostream>
#include <string>
#include <algorithm>
#include <iterator>

using namespace std;

int main()
{
  //I create an iterator that retrieves `string` objects from `cin`
  auto begin = istream_iterator<string>(cin);
  //I create an iterator that represents the end of a stream
  auto end = istream_iterator<string>();
  //and iterate over the file, and copy those elements into my `set`
  set<string> myset(begin, end);

  //this line copies the elements in the set to `cout`
  //I have this to verify that I did it all right
  copy(myset.begin(), myset.end(), ostream_iterator<string>(cout, "\n"));
  return 0;
}

http://ideone.com/iz1q0

Answer 2

Assuming you've read your file into a string, boost::split will do the trick:

#include <set>
#include <boost/foreach.hpp>
#include <boost/algorithm/string.hpp>

std::string astring = "abc 123 abc 123\ndef 456 def 456";  // your string
std::set<std::string> tokens;                              // this will receive the words
boost::split(tokens, astring, boost::is_any_of("\n "));    // split on space & newline

// Print the individual words
BOOST_FOREACH(std::string token, tokens){
    std::cout << "\n" << token << std::endl;
}

Lists or Vectors can be used instead of a Set if necessary.

Also note this is almost a dupe of: Split a string in C++?