multiset
原文出自http://blog.csdn.net/longshengguoji/article/details/8546286
使用set或multiset之前，必须加入头文件<set>
multiset中允许有重复元素。
std::set<int> myset;
std::set<int>::iterator it;
std::pair<std::set<int>::iterator,bool> ret;
bool empty() const:判断容器是否为空，若返回true，表明容器已空
pair<iterator,bool> insert( x):插入元素x ret= myset.insert(20); //这里返回一对迭代器，if(没有成功插入(myset里已有20)) 那么ret.second==false
iterator insert(iterator it,x):在迭代器it处插入元素x myset.insert (it,25);
void insert(const value_type *first,const value_type *last):插入[first, last)之间元素
iterator erase(iterator it):删除迭代器指针it处元素
iterator erase(iterator first,iterator last):删除[first, last)之间元素
size_type erase(const Key& key):删除元素值等于key的元素
#include <iostream>
#include <set>
int main ()
{
std::set<int> myset;
std::set<int>::iterator it;
std::pair<std::set<int>::iterator,bool> ret;
// set some initial values:
for (int i=1; i<=5; ++i) myset.insert(i*10); // set: 10 20 30 40 50
ret = myset.insert(20); // no new element inserted
if (ret.second==false) it=ret.first; // "it" now points to element 20
myset.insert (it,25); // max efficiency inserting
myset.insert (it,24); // max efficiency inserting
myset.insert (it,26); // no max efficiency inserting
int myints[]= {5,10,15}; // 10 already in set, not inserted 实现数组插入
myset.insert (myints,myints+3);
std::cout << "myset contains:";
for (it=myset.begin(); it!=myset.end(); ++it)
std::cout << ' ' << *it;
std::cout << '\n';
return 0;
}
#include <iostream>
#include <set>
int main ()
{
std::set<int> myset;
std::set<int>::iterator it;
// insert some values:
for (int i=1; i<10; i++) myset.insert(i*10); // 10 20 30 40 50 60 70 80 90
it = myset.begin();
++it; // "it" points now to 20
myset.erase (it);
myset.erase (40);
it = myset.find (60);
myset.erase (it, myset.end());
std::cout << "myset contains:";
for (it=myset.begin(); it!=myset.end(); ++it)
std::cout << ' ' << *it;
std::cout << '\n';
return 0;
}
4) 遍历函数
iterator begin():返回首元素的迭代器指针
iterator end()：返回尾元素的迭代器指针
reverse_iterator rbegin():返回尾元素的逆向迭代器指针
reverse_iterator rend():返回首元素前一个位置的迭代器指针
#include <iostream>
#include <set>
int main ()
{
int myints[] = {75,23,65,42,13};
std::set<int> myset (myints,myints+5);
std::cout << "myset contains:";
for (std::set<int>::iterator it=myset.begin(); it!=myset.end(); ++it)
std::cout << ' ' << *it;
std::cout << '\n';
return 0;
}
5) 操作函数
const_iterator lower_bound(const Key& key):返回容器中大于等于key的迭代器指针
const_iterator upper_bound(const Key& key):返回容器中大于key的迭代器指针
int count(const Key& key) const:返回容器中元素等于key的元素的个数
pair<const_iterator,const_iterator> equal_range(const Key& key) const:返回容器中元素值等于key的迭代指针[first, last)
const_iterator find(const Key& key) const:查找功能，返回元素值等于key的迭代器指针
void swap(set& s):交换集合元素
void swap(multiset& s):交换多集合元素
#include <iostream>
#include <set>
int main ()
{
std::set<int> myset;
std::set<int>::iterator itlow,itup;
for (int i=1; i<10; i++) myset.insert(i*10); // 10 20 30 40 50 60 70 80 90
itlow=myset.lower_bound (30); // ^
itup=myset.upper_bound (60); // ^
myset.erase(itlow,itup); // 10 20 70 80 90
std::cout << "myset contains:";
for (std::set<int>::iterator it=myset.begin(); it!=myset.end(); ++it)
std::cout << ' ' << *it;
std::cout << '\n';
return 0;
}
#include "stdafx.h"
#include <iostream>
#include <set>
using namespace std;
int main ()
{
int myints[]={12,75,10,32,20,25};
set<int> first (myints,myints+3); // 10,12,75
set<int> second (myints+3,myints+6); // 20,25,32
first.swap(second);
cout << "first contains:";
for (set<int>::iterator it=first.begin(); it!=first.end(); ++it)
cout << ' ' << *it;
cout << '\n';
cout << "second contains:";
for (set<int>::iterator it=second.begin(); it!=second.end(); ++it)
cout << ' ' << *it;
cout << '\n';
return 0;
}