c++ set使用

#include <iostream>
#include <set>

using namespace std;

// 仿函数, 重载函数调用运算符()的类
class MyFang{
public:
    bool operator() (int v1, int v2) {
        return v1 > v2;
    }
};

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

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

void test01() {

//    set<int, 排序规则> s1;    // 默认是从小到大.
    set<int, MyFang> s1;        // 从大到小排序, 使用仿函数.
    s1.insert(30);
    s1.insert(10);
    s1.insert(40);
    s1.insert(4);
    s1.insert(21);
    printSetInt(s1);

    cout << "test01 end ..." << endl;
}

class PersonFang;       // 提前声明
class PersonObj{
    friend class PersonFang;        // 友元类
    friend void printSetPersonObj(set<PersonObj, PersonFang> &s);   // 友元函数
private:
    int num;
    string name;
    float score;
public:
    PersonObj(){};
    PersonObj(int num, string name, float score) {
        this->num = num;
        this->name = name;
        this->score = score;
    }
};

// 仿函数, 重载函数调用运算符()的类
class PersonFang {
public:
    bool operator() (PersonObj v1, PersonObj v2) {  // 仿函数
        return v1.num > v2.num;
    }
};

void printSetPersonObj(set<PersonObj, PersonFang> &s){
    set<PersonObj, PersonFang>::const_iterator it = s.begin();
    for(; it != s.end(); it++) {
        cout << (*it).num << "-" << (*it).name << "-" << (*it).score << " ";
    }
    cout << endl;
}

void test02() {
    set<PersonObj, PersonFang> s1;
    s1.insert(PersonObj(108, "luck", 99.2f));
    s1.insert(PersonObj(10, "lucka", 919.2f));
    s1.insert(PersonObj(1040, "luckb", 929.2f));
    s1.insert(PersonObj(1, "luckc", 939.2f));
    s1.insert(PersonObj(67, "luckd", 949.2f));
    printSetPersonObj(s1);

    cout << "test02 end ..." << endl;
}

void test03() {
    set<int> s1;
    s1.insert(10);
    s1.insert(30);
    s1.insert(50);
    s1.insert(70);
    s1.insert(90);
    printSetIntOnly(s1);
    set<int>::const_iterator ret;
    ret = s1.find(50);  // 查找元素是否存在，返回该元素的迭代器，无返回尾迭代器.
    if (ret != s1.end()) {
        cout << "找到的结果为：" << *ret << endl;
    }
    cout << "元素的个数：" << s1.count(50) << endl;

    ret = s1.lower_bound(50);
    if (ret != s1.end()) {
        cout << "下限为：" << *ret << endl;
    }
    ret = s1.upper_bound(50);
    if(ret != s1.end()) {
        cout << "上限为：" << *ret << endl;
    }
    // 以对组 的方式 存储上下限 pair
    pair< set<int>::const_iterator, set<int>::const_iterator > pa;
    pa = s1.equal_range(50);
    if (pa.first != s1.end()) {
        cout << "下限为：" << *(pa.first) << endl;
    }
    if (pa.second != s1.end()) {
        cout << "上限为：" << *(pa.second) << endl;
    }
    cout << "test03 end ..." << endl;
}

void test04() {
    multiset<int> sm;   // 可有重复元素的set
    sm.insert(10);
    sm.insert(20);
    sm.insert(10);
    sm.insert(30);
    multiset<int>::const_iterator it = sm.begin();
    for(; it != sm.end(); it++) {
        cout << *it <<endl;
    }
    cout << "test04 end ..." << endl;
}

void test05(){
    // 方式一.
    pair<int, string> p1(1003, "移动");
    pair<int, string> p2(1004, "电信");
    pair<int, string> p3(1005, "两");

    // 方式二
    pair<int, string> p4 = make_pair(9876, "新新");

    cout << p4.first << " - " << p4.second << endl;
    cout << "test05 end ..." << endl;
}

int main() {
    test01();
    test02();
    test03();
    test04();
    test05();
    return 0;
}