[C++STL]set容器用法介绍

Posted 2021-06-27 Wecccccccc

代码如下:

#include <iostream>
#include <set>
using namespace std;

void printSet(set<int>&s)
{
	for (set<int>::iterator it = s.begin(); it != s.end(); it++)
	{
		cout << *it << " ";
	}
	cout << endl;
}

void test01()
{
	set<int>s1;
	s1.insert(10);
	s1.insert(10);
	s1.insert(30);
	s1.insert(20);
	s1.insert(40);
	printSet(s1);

	set<int>s2(s1);
	printSet(s2);

	set<int>s3;
	s3 = s2;
	printSet(s3);

}

int main()
{
	test01();
	return 0;
}

测试结果:

总结:

代码如下:

#include <iostream>
#include <set>
using namespace std;

void printSet(set<int>&s)
{
	for (set<int>::iterator it = s.begin(); it != s.end(); it++)
	{
		cout << *it << " ";
	}
	cout << endl;
}

void test01()
{
	set<int>s1;
	s1.insert(10);
	s1.insert(30);
	s1.insert(20);
	s1.insert(40);

	if (s1.empty())
	{
		cout << "s1 empty" << endl;
	}
	else
	{
		cout << "s1 no empty" << endl;
		cout << "s1 size = " << s1.size() << endl;
	}

	set<int>s2;
	s2.insert(100);
	s2.insert(300);
	s2.insert(200);
	s2.insert(400);

	cout << "交换前" << endl;
	printSet(s1);
	printSet(s2);
	cout << "交换后" << endl;
	s1.swap(s2);
	printSet(s1);
	printSet(s2);
}




int main()
{
	test01();
	return 0;
}

测试结果:

总结:

代码如下:

#include <iostream>
#include <set>
using namespace std;

void printSet(set<int>&s)
{
	for (set<int>::iterator it = s.begin(); it != s.end(); it++)
	{
		cout << *it << " ";
	}
	cout << endl;
}

void test01()
{
	set<int>s1;
	s1.insert(10);
	s1.insert(30);
	s1.insert(20);
	s1.insert(40);
	printSet(s1);

	s1.erase(s1.begin());
	printSet(s1);

	s1.erase(30);
	printSet(s1);

	s1.clear();
	printSet(s1);

}




int main()
{
	test01();
	return 0;
}

测试结果:

总结:

插入 — insert
删除 — erase
清空 — clear

代码如下:

#include <iostream>
#include <set>
using namespace std;

void printSet(set<int>&s)
{
	for (set<int>::iterator it = s.begin(); it != s.end(); it++)
	{
		cout << *it << " ";
	}
	cout << endl;
}

void test01()
{
	set<int>s1;
	s1.insert(10);
	s1.insert(30);
	s1.insert(20);
	s1.insert(40);

	set<int>::iterator pos = s1.find(30);
	if (pos != s1.end())
	{
		cout << "find elem" << *pos<<endl;
	}
	else
	{
		cout << "no find elem" << endl;
	}

	int num = s1.count(30);
	cout << "num = " << num << endl;


}




int main()
{
	test01();
	return 0;
}

测试结果:

总结:

代码如下:

#include <iostream>
#include <set>
using namespace std;

void printSet(set<int>&s)
{
	for (set<int>::iterator it = s.begin(); it != s.end(); it++)
	{
		cout << *it << " ";
	}
	cout << endl;
}

void test01()
{
	set<int>s;
	pair<set<int>::iterator, bool> ret = s.insert(10);
	if (ret.second)
	{
		cout << "success 1" << endl;
	}
	else
	{
		cout << "fail 1" << endl;
	}

	ret = s.insert(10);

	if (ret.second)
	{
		cout << "success 2" << endl;
	}
	else
	{
		cout << "fail 2" << endl;
	}

	multiset<int>ms;
	ms.insert(10);
	ms.insert(10);

	for (multiset<int>::iterator it = ms.begin(); it != ms.end(); it++)
	{
		cout << *it << " ";
	}
	cout << endl;
}




int main()
{
	test01();
	return 0;
}

测试结果:

总结:

set存放内置数据类型

代码如下:

#include <iostream>
#include <set>
using namespace std;

void printSet(set<int>&s)
{
	for (set<int>::iterator it = s.begin(); it != s.end(); it++)
	{
		cout << *it << " ";
	}
	cout << endl;
}

class cmp
{
public:
	bool operator()(int a, int b)
	{
		return a > b;
	}
};

void test01()
{
	set<int>s1;
	s1.insert(10);
	s1.insert(40);
	s1.insert(20);
	s1.insert(30);
	s1.insert(50);

	for (set<int>::iterator it = s1.begin(); it != s1.end(); it++)
	{
		cout << *it << " ";
	}
	cout << endl;

	set<int, cmp>s2;
	s2.insert(10);
	s2.insert(40);
	s2.insert(20);
	s2.insert(30);
	s2.insert(50);

	for (set<int, cmp>::iterator it = s2.begin(); it != s2.end(); it++)
	{
		cout << *it << " ";
	}
	cout << endl;

}




int main()
{
	test01();
	return 0;
}

测试结果:

总结:
利用仿函数可以指定set容器的排序规则。

set存放自定义数据类型
代码如下:

#include <iostream>
#include <string>
#include <set>
using namespace std;

void printSet(set<int>&s)
{
	for (set<int>::iterator it = s.begin(); it != s.end(); it++)
	{
		cout << *it << " ";
	}
	cout << endl;
}

class Person
{
public:
	Person(string name, int age):myName(name),myAge(age){}

	string myName;
	int myAge;
};

class cmp
{
public:
	bool operator()(const Person & a, const Person &b)
	{
		return a.myAge > b.myAge;
	}
};


void test01()
{
	set<Person, cmp> s;
	typedef set<Person, cmp> setpc;

	Person p1("Tom", 23);
	Person p2("Mike", 27);
	Person p3("Bom", 25);
	Person p4("Jack", 21);

	s.insert(p1);
	s.insert(p2);
	s.insert(p3);
	s.insert(p4);

	for (setpc::iterator it = s.begin(); it != s.end(); it++)
	{
		cout << "name = " << it->myName << "age = " << it->myAge << endl;
	}
}




int main()
{
	test01();
	return 0;
}

测试结果：

总结:

对于自定义数据类型，set必须指定排序规则才可以插入数据。