STL系列 set

set is a container that NOT allow same element, while multiset allows .

feature : binary tree .

here example of contains almost all functions:

#include <set>
#include <iostream>
using namespace std;
//display in order
void display_all(const multiset<int> &li)
{
    multiset<int>::const_iterator iter;
    for(iter = li.begin(); iter!= li.end(); iter++)
        cout << *iter << " , ";
    cout << "\n";    
}
//display in rorder
void display_all_r(const multiset<int> &li)
{
    multiset<int>::const_reverse_iterator riter;
    for(riter = li.rbegin(); riter!= li.rend(); riter++)
        cout << *riter << " , ";
    cout << "\n";    
}

int main()
{
    //default constructor
    multiset<int> c1;
    int ai[] = {0,0,1,1,2,2,3,4};
    //with range
    multiset<int> c2(ai ,ai+8);
    multiset<int> c3(c2);
    multiset<int>::iterator iter;    
    if(c1.empty())
        cout << "multiset c1 is empty \n" ;
    else
        cout << "multiset c1 is NOT empty \n" ;
        
    cout << "c2 (use begin ,end) = ";
    display_all(c2);
    cout << "c2 (use rbegin ,rend) = ";
    display_all_r(c2);
    
    c1.insert(ai, ai+4);
    c1.insert(1);
    cout << "Number elements in c1 that match 1 = " << c1.count(1) << endl;
    
    //find
    multiset<int>::const_iterator citer  = c1.find(3);
    if(citer != c1.end())
        cout <<"c1 contains element3, *citer = "<< *citer << "\n";
    
    cout << "c1.max_size = " << c1.max_size() << "\n";
    
    c1.insert(4);
    c2.swap(c1);
    
    cout<< "The last element of c2 = " << *(c2.rbegin()) << endl;
    
    c1.clear();
    cout << "after clear c1.size = " << c1.size() << endl;
    
    //get_allocator
    multiset<int>::allocator_type a1 = c1.get_allocator();
    
    c2.insert(7);
    c2.insert(8);    
    //key_compare
    multiset<int>::key_compare kc = c2.key_comp();
    bool result = kc(2,3);
    if(result)
        cout << "kc is function object used by c2. kc(2,3) = true \n" ;
    else
        cout << "kc is function object used by c2. kc(2,3) = false \n" ;
    
    //val_compare
    multiset<int>::value_compare vc = c2.value_comp();
    result = vc(12,3);
    if(result)
        cout << "vc is function object used by c2. vc(12,3) = true \n" ;
    else
        cout << "vc is function object used by c2. vc(12,3) = false \n" ;
    
    cout<< "*(c2.upper_bound(4))" << *(c2.upper_bound(4)) << endl;
    cout<< "*(c2.lower_bound(4))" << *(c2.lower_bound(4)) << endl;
    
    pair<multiset<int>::const_iterator , multiset<int>::const_iterator> pr1 = c2.equal_range(3) ;
    cout<< "*(pr1.first) = " << *(pr1.first) << "\t" <<  " *(pr1.second) " <<*(pr1.second) << endl;
    
    if(c3.erase(1)!= 0)
        cout << "c3 does not contain 1 anymore\n";
    else
        cout <<  "No elements in c3 match key 1";
    
    int c2begin = *(c2.begin()) ;
    cout << "*(c2.begin()) = "<< c2begin << endl;
    
    c2.erase(c2.begin());
    c2.count(c2begin);
    //if(( c2.erase(c2.begin())) != c2.end())
    if(c2.count(c2begin) == 0)
        cout << "c2 does not contain "<< c2begin<<" anymore\n";
    else
        cout <<  "No elements in c2 match key " << c2begin;
        
    c3.erase(c3.begin(), c3.end());
    cout << "after c3.erase(c3.begin(), c3.end()) c3.size() = " << c3.size() << "\n";
    
    //set does NOT allow to contain 2 same key
    set<int> si;    
    pair<set<int>::iterator, bool> prs;
    for(int inserttimes = 0; inserttimes < 2; inserttimes ++)
    {
        prs = si.insert(1);
        if(prs.second)//true ----it was actully insert
            cout << "element 1 was insert in s1 successfully" << endl;
        else
            cout << "element 1 already exists in c1 and *(prs.first) = " << *(prs.first) << endl; //first --- point to the element
    }
}