Thread: set?

what is wrong with the following?

Code:

#include <algorithm>
#include <iostream>
#include <list>
#include <set>
#include <string>
using namespace std;

int main()
{
	typedef set<string> WordSet;
	typedef WordSet::iterator WordIter;
	typedef list<WordIter> Index;
	WordSet words;
	Index input_order;
	
	for (string new_word; cin >> new_word, new_word != "Quit";)
	{
		pair<WordIter, bool> &trace = words.insert(new_word);
		if (trace.second)
			input_order.push_back(trace.first);
	}
	
	copy(input_order.begin(), input_order.end(),
		ostream_iterator<string>(cout, "\n"));
	copy(words.begin(), words.end(),
		ostream_iterator<string>(cout, "\n"));
	return 0;
}

when I try to compile I get an error at line 18...
Illegal Implicit conversion

why? I dont get it..


Im using code warior 7.0 on mac os X..

Luigi
thx..

with all those unnecessary typedefs you must be looking forward to a career in Windows@ programming. 8-)

If I counted right line 18 is this:

pair<WordIter, bool> &trace = words.insert(new_word);

In the future you're likely to get better quality and more abundant answers if you actually flag/highlight the offending line for anyone willing to look at the problem.

The potential problem I have with this line is that I believe the insert method for STL sets returns void. Therefore trying to assign type void to a reference to a pair is an implicit conversion.

Here's a slightly different function to accomplish what I think you were trying to do, words will be in "ascending" order from smallest string to largest input_order will maintain the chronological sequence of the string as they are inserted into the set, irrespective of the size of of the string.

for (string new_word; cin >> new_word, new_word != "Quit"
{
if(count(new_word) == 0)
{
words.insert(new_word);
input_order.push_back(new_word);
}
}