C++ |关联容器set的常用函数操作

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

struct strLess
{
	bool operator() (const char *s1, const char *s2) const
	{
		return strcmp(s1, s2) < 0;
	}
};

void printSet(set<int> s)
{
	ostream_iterator<int>iter(cout,",");
	copy(s.begin(), s.end(), iter);

	// set<int>::iterator iter;
	// for (iter = s.begin(); iter != s.end(); iter++)
	//    //cout<<"set["<<iter-s.begin()<<"]="<<*iter<<", "; //Error
	//    cout<<*iter<<", ";
	cout << endl;
}

void main()
{
	//创建set对象，共5种方式，提示如果比较函数对象及内存分配器未出现，即表示采用的是系统默认方式
	//创建空的set对象，元素类型为int，
	set<int> s1;
	
	//创建空的set对象，元素类型char*，比较函数对象(即排序准则)为自定义strLess
	set<const char*, strLess> s2(strLess);
	
	//利用set对象s1,拷贝生成set对象s2
	set<int> s3(s1);
	
	//用迭代区间[&first, &last)所指的元素，创建一个set对象
	int iArray[] = { 13, 32, 19 };
	set<int> s4(iArray, iArray + 3);
	
	//用迭代区间[&first, &last)所指的元素，及比较函数对象strLess，创建一个set对象
	const char* szArray[] = { "hello", "dog", "bird" };
	set<const char*, strLess> s5(szArray, szArray + 3, strLess());

	//元素插入：
	//1,插入value，返回pair配对对象，可以根据.second判断是否插入成功。(提示:value不能与set容器内元素重复)
	//pair<iterator, bool> insert(value)
	//2,在pos位置之前插入value，返回新元素位置，但不一定能插入成功
	//iterator insert(&pos, value)
	//3,将迭代区间[&first, &last)内所有的元素，插入到set容器
	//void insert[&first, &last)


	cout << "s1.insert() : " << endl;
	for (int i = 0; i <5; i++)
		s1.insert(i * 10);
	printSet(s1);

	cout << "s1.insert(20).second = " << endl;;
	if (s1.insert(20).second)
		cout << "Insert OK!" << endl;
	else
		cout << "Insert Failed!" << endl;

	cout << "s1.insert(50).second = " << endl;
	if (s1.insert(50).second)
	{
		cout << "Insert OK!" << endl; printSet(s1);
	}
	else
		cout << "Insert Failed!" << endl;

	cout << "pair<set<int>::iterator, bool> p;\np = s1.insert(60);\nif (p.second):" << endl;
	pair<set<int>::iterator, bool> p;// second为判断标志 bool类型
	p = s1.insert(60);
	if (p.second)
	{
		cout << "Insert OK!" << endl; printSet(s1);
	}
	else
		cout << "Insert Failed!" << endl;


	//元素删除
	//1,size_type erase(value) 移除set容器内元素值为value的所有元素，返回移除的元素个数
	//2,void erase(&pos) 移除pos位置上的元素，无返回值
	//3,void erase(&first, &last) 移除迭代区间[&first, &last)内的元素，无返回值
	//4,void clear()， 移除set容器内所有元素


	cout << "\ns1.erase(70) = " << endl;
	s1.erase(70);
	printSet(s1);
	cout << "s1.erase(60) = " << endl;
	s1.erase(60);
	printSet(s1);

	cout << "set<int>::iterator iter = s1.begin();\ns1.erase(iter) = " << endl;
	set<int>::iterator iter = s1.begin();
	s1.erase(iter);
	printSet(s1);


	//元素查找
	//count(value)返回set对象内元素值为value的元素个数
	//iterator find(value)返回value所在位置，找不到value将返回end()
	
	
	cout << "\ns1.count(10) = " << s1.count(10) << ", s1.count(80) = " << s1.count(80) << endl;
	cout << "s1.find(10) : ";
	if (s1.find(10) != s1.end())
		cout << "OK!" << endl;
	else
		cout << "not found!" << endl;

	cout << "s1.find(80) : ";
	if (s1.find(80) != s1.end())
		cout << "OK!" << endl;
	else
		cout << "not found!" << endl;


	//其它常用函数
	cout << "\ns1.empty()=" << s1.empty() << ", s1.size()=" << s1.size() << endl;
	set<int> s9;
	s9.insert(100);
	cout << "s1.swap(s9) :" << endl;
	s1.swap(s9);
	cout << "s1: " << endl;
	printSet(s1);
	cout << "s9: " << endl;
	printSet(s9);
}

运行结果：