C++ primer超详细讲解关联容器

map<string, size_t>word_count;
string word;
while (cin >> word)
	++word_count[word];
for (const auto& w : word_count)
	cout << w.first << " occurs " << w.second << " 次 " << endl;

//忽略exclude中的单词进行计数
map<string, size_t>word_count;
set<string> exclude = { "the","but" };
string word;
while (cin >> word)
	if(exclude.find(word)==exclude.end())
//find返回一个迭代器，指向该关键字，若不存在，则返回尾后迭代器
		++word_count[word];
for (const auto& w : word_count)
	cout << w.first << " occurs " << w.second << " 次 " << endl;

vector<int> v;
for (int i = 0; i != 10; i++)
{
	v.push_back(i);
	v.push_back(i);
}
set<int> is(v.begin(), v.end());
multiset<int> ms(v.begin(), v.end());
cout << is.size() << endl;  //输出10
cout << ms.size() << endl;  //输出20
cout << v.size() << endl;   //输出20

pair<string,int> process(vector<string> &v)
{
    //处理v
    if(!v.empty())
        return { v.back(),v.back().size()}  //列表初始化
    else
        return pair<string,int>(); //隐式构造返回值
}

map<string,int> v;
auto map_it=v.begin()  //获取一个指向v中一个元素的迭代器
//map_it是指向一个pair<const string,size_t>对象的引用
cout<<map_it->first;  //打印此元素的关键字
cout<<map_it->second  //打印此元素的值

set<int> s = { 0,1,2,3,4,5,6 };
set<int>::iterator it = s.begin();
if (it != s.end())
{
	*it = 42;  //无法修改
	cout << *it << endl;
}

vector<int> ivec={2,4,6,8}
set<int> set2;
set2.insert(ivec.begin(),ivec.end())
set2.insert({1,3,5,7})