set_union()

set_union() constructs a sorted sequence of the element values contained within the two sequences. For example, given the two sequences {0,1,2,3} and {0,2,4,6}, the set union is {0,1,2,3,4,6}. If the element is present in both containers, such as 0 and 2 in the example, the element of the first container is copied.

#include <algorithm> 


string str1[] = { "Pooh", "Piglet", "Tigger", "Eeyore" }; 


string str2[] = { "Pooh", "Heffalump", "Woozles" }; 


set<string> set1( str1, str1+4 ), 


            set2( str2, str2+3 ); 





// holds result of each set operation 


set<string> res; 





//set_union(): Eeyore Heffalump Piglet Pooh Tigger Woozles 


set_union( set1.begin(), set1.end(), 


           set2.begin(), set2.end(), inserter(res,res.begin())); 





res.clear(); // empties the container of elements 





// set_intersection(): Pooh 


set_intersection( set1.begin(), set1.end(), set2.begin(), 


                  set2.end(), inserter( res,res.begin() )); 





res.clear(); 





// set_difference(): Eeyore Piglet Tigger 


set_difference( set1.begin(), set1.end(), set2.begin(), 


                set2.end(), inserter( res, res.begin() )); 





res.clear(); 





// set_symmetric_difference(): 


//    Eeyore Heffalump Piglet Tigger Woozles 


set_symmetric_difference( set1.begin(), set1.end(), set2.begin(), 


                          set2.end(), inserter( res, res.begin() ));