【C++深度探索】map与set的基础介绍与实用指南

#include<set>
#include<vector>
int main()
{
	//构造空的set
	set<int> s1;

	//用[first, last)区间中的元素构造
	vector<int> v = { 0,1,2,3,4,5,6,7 };
	set<int> s2(v.begin(), v.end());

	//set的拷贝构造
	set<int> s3(s2);
	return 0;
}

#include<set>
#include<vector>
int main()
{
	//用[first, last)区间中的元素构造
	vector<int> v = { 0,1,2,3,4,5,6,7 };
	set<int> s(v.begin(), v.end());

	//正向迭代器遍历
	set<int>::iterator it = s.begin();
	while (it != s.end())
	{
		cout << *it << " ";
		++it;
	}
	cout << endl;
	//反向迭代器遍历
	set<int>::reverse_iterator rit = s.rbegin();
	while (rit != s.rend())
	{
		cout << *rit << " ";
		++rit;
	}

	return 0;
}

#include <set>
void TestSet()
{
	//创建一个set容器
	set<int> s;

	//插入数值
	s.insert(1);
	s.insert(3);
	s.insert(5);
	s.insert(7);
	s.insert(7);

	//查看s中元素个数
	cout <<"size:"<< s.size() << endl;

	// 正向打印set中的元素，从打印结果中可以看出：set可去重
	cout << "s:";
	for (auto& e : s)
		cout << e << " ";
	cout << endl;

	// set中值为7的元素出现了几次
	cout << "7出现的次数：" << s.count(7) << endl;

	//使用set中存储的数值删除元素
	s.erase(7);
	//使用迭代器删除
	s.erase(s.begin());

	cout << "删除元素后s:";
	for (auto& e : s)
		cout << e << " ";
	cout << endl;


	// 用数组array中的元素构造set
	int array[] = { 1, 3, 5, 7, 9, 2, 4, 6, 8, 0, 1, 3, 5, 7, 9, 2, 4,6, 8, 0 };
	set<int> s1(array, array + sizeof(array) / sizeof(array[0]));

	//清空s中的元素
	s.clear();

	//交换s和s1
	s.swap(s1);
	cout << "交换后s：";
	for (auto& e : s)
		cout << e << " ";
	cout << endl;

	//找到元素3并删除
	s.erase(s.find(3));
	cout << "删除3后s：";
	for (auto& e : s)
		cout << e << " ";
	cout << endl;

	//找到1到5的位置,并删除该区间中的值
	s.erase(s.find(1), s.find(5));//左闭右开
	cout << "删除1~5后s：";
	for (auto& e : s)
		cout << e << " ";
	cout << endl;
	
}

#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 <set>
int main()
{
	multiset<int> m = { 1,5,3,5,4,5,2,6,1,7 };

	auto pos = m.find(5);
	while (pos != m.end() && *pos == 5)
	{
		cout << *pos << " ";
		++pos;
	}
	cout << endl;
	cout << m.count(5);
	return 0;
}

#include <set>
int main()
{
	multiset<int> m = { 1,5,3,5,4,5,2,6,1,7 };

	cout << "删除前：";
	for (auto i : m)
	{
		cout << i << " ";
	}
	cout << endl;

	//删除5
	m.erase(5);
	cout << "删除后：";
	for (auto i : m)
	{
		cout << i << " ";
	}
	return 0;
}

//SGI - STL中关于键值对的定义：
template <class T1, class T2>
struct pair
{
	typedef T1 first_type;
	typedef T2 second_type;
	T1 first;
	T2 second;
	//默认构造
	pair() : first(T1()), second(T2())
	{}
	//带参构造
	pair(const T1& a, const T2& b) : first(a), second(b)
	{}
};

#include<map>
#include<vector>
int main()
{
	//构造空的map
	map<string, string> m1;

	//使用迭代器构造器
	vector<pair<string, string>> v = {{"上", "up"}, { "下", "down"}, { "左", "left"}, { "右", "right"}};
	map<string, string> m2(v.begin(),v.end());

	//拷贝构造
	map<string, string> m3(m2);
	return 0;
}

#include<map>
#include<vector>
int main()
{
	//使用迭代器构造器
	vector<pair<string, string>> v = { {"上", "up"}, { "下", "down"}, { "左", "left"}, { "右", "right"} };
	map<string, string> m(v.begin(), v.end());

	//正向迭代器遍历
	cout << "正向迭代器遍历: ";
	map<string, string>:: iterator it = m.begin();
	while (it != m.end())
	{
		cout << it->first << "->" << it->second << " ";
		++it;
	}

	//反向迭代器遍历
	cout << endl << endl;;
	cout << "反向迭代器遍历: ";
	map<string, string>::reverse_iterator rit = m.rbegin();
	while (rit != m.rend())
	{
		cout << rit->first << "->" << rit->second << " ";
		++rit;
	}


	return 0;
}

#include<map>
#include<vector>
int main()
{
	//迭代器构造
	vector<pair<string, string>> v = { {"上", "up"}, { "下", "down"}, { "左", "left"}, { "右", "right"} };
	map<string, string> m(v.begin(), v.end());
	
	cout << m["上"] << endl;
	cout << m["下"] << endl;
	cout << m["左"] << endl;
	cout << m["右"] << endl;

	return 0;
}

#include<map>
#include<vector>
int main()
{
	//迭代器构造
	vector<pair<string, string>> v = { {"上", "up"}, { "下", "down"}, { "左", "left"}, { "右", "right"} };
	map<string, string> m(v.begin(), v.end());
	
	//借用operator[]向map中插入元素
	m["北"] = "north";
	// 将<"北", "">插入map中，插入成功，返回value的引用，将“north”赋值给该引用结果
	
	//遍历打印
	map<string, string>:: iterator it = m.begin();
	while (it != m.end())
	{
		cout << it->first << "->" << it->second << " ";
		++it;
	}
	return 0;
}

map<string, string> m;
m.insert("dog", "狗");//这样是错误的

	map<string, string> m;
	//m.insert("dog", "狗");//错误
	
	// 向map中插入元素的方式：
	//1.创建一个有名对象
	pair<string, string> kv1("dragon", "龙");
	m.insert(kv1);

	//2.匿名对象插入
	m.insert(pair<string, string>("lion", "狮子"));

	//3.使用pair提供的函数模板make_pair来构造键值对
	m.insert(make_pair("tiger", "老虎"));

	//4.多参数的隐式类型转换
	m.insert({"pig","猪"})

#include <string>
#include <map>
void TestMap()
{
	map<string, string> m;
	//m.insert("dog", "狗");//错误
	
	// 向map中插入元素的方式：
	//1.创建一个有名对象
	pair<string, string> kv1("dragon", "龙");
	m.insert(kv1);

	//2.匿名对象插入
	m.insert(pair<string, string>("lion", "狮子"));

	//3.使用pair提供的函数模板make_pair来构造键值对
	m.insert(make_pair("tiger", "老虎"));

	//4.多参数的隐式类型转换
	m.insert({ "pig","猪" });
	
	// 用迭代器去遍历map中的元素，可以得到一个按照key排序的序列
	for (auto& e : m)
		cout << e.first << "->" << e.second << endl;
	cout << endl;


	// map中的键值对key一定是唯一的，如果key存在将插入失败
	auto ret = m.insert(make_pair("lion", "大师"));
	if (ret.second)
		cout << "<lion, 大师>不在map中, 已经插入" << endl;
	else
		cout << "键值为lion的元素已经存在：" << ret.first->first << "->"
		<< ret.first->second << " ，插入失败" << endl;


	// 删除key为"apple"的元素
	m.erase("tiger");
	if (1 == m.count("tiger"))
		cout << "tiger还在" << endl;
	else
		cout << "tiger不在" << endl;
}

#include <string>
#include <map>
void TestMultiMap()
{
	multimap<string, string> m;

	m.insert({ "rose","玫瑰" });
	m.insert({ "lily","百合" });
	m.insert({ "peony","牡丹" });
	m.insert({ "cherry","樱花" });
	m.insert({ "lris","鸢尾花" });

	//插入完全相同的键值对
	m.insert({ "cherry","樱花" });

	//插入只有键相同，值不同
	m.insert({ "cherry","樱桃" });

	//插入值相同，键不同
	m.insert({ "yingtao","樱桃" });




	// 用迭代器去遍历map中的元素，可以得到一个按照key排序的序列
	for (auto& e : m)
		cout << e.first << "->" << e.second << endl;
	cout << endl;
}

#include <string>
#include <map>
void TestMultiMap()
{
	multimap<string, string> m;

	m.insert({ "rose","玫瑰" });
	m.insert({ "lily","百合" });
	m.insert({ "peony","牡丹" });
	m.insert({ "cherry","樱花" });
	m.insert({ "lris","鸢尾花" });

	//插入完全相同的键值对
	m.insert({ "cherry","樱花" });

	//插入只有键相同，值不同
	m.insert({ "cherry","樱桃" });

	//插入值相同，键不同
	m.insert({ "yingtao","樱桃" });

	//查看键为cherry的元素个数
	cout << "cherry:" << m.count("cherry") << endl;
}

#include <string>
#include <map>
void TestMultiMap()
{
	multimap<string, string> m;

	m.insert({ "rose","玫瑰" });
	m.insert({ "lily","百合" });
	m.insert({ "peony","牡丹" });
	m.insert({ "cherry","樱花" });
	m.insert({ "lris","鸢尾花" });

	//插入完全相同的键值对
	m.insert({ "cherry","樱花" });

	//插入只有键相同，值不同
	m.insert({ "cherry","樱桃" });

	//插入值相同，键不同
	m.insert({ "yingtao","樱桃" });

	//查看键为cherry的元素个数
	cout << "cherry:" << m.count("cherry") << endl;

	// 删除key为"cherry"的元素
	m.erase("cherry");
	if (1 == m.count("cherry"))
		cout << "cherry还在" << endl;
	else
		cout << "cherry不在" << endl;

	// 用迭代器去遍历map中的元素，可以得到一个按照key排序的序列
	for (auto& e : m)
		cout << e.first << "->" << e.second << endl;
	cout << endl;
}