This is how you can insert elements in a container, without repetition, and obtaining unique ids. Useful for inserting vertexes in Boost.Graph. See http://stackoverflow.com/questions/3950841

unique_insert_with_ids.cpp

#include <iostream>
#include <string>
#include <map>

using namespace std;

int main (int argc, char const *argv[])
{
	
	string array[] = { "zero", "one", "one", "zero", "two", "three", "zero" };
	map<string, unsigned int> numbers;
	for(size_t i = 0; i < 7; ++i)
	{
		pair<string, unsigned int> p(array[i], numbers.size());
		int id = numbers.insert(p).first->second;
		cout << array[i] << "\t" << id << endl;
	}
	return 0;
}