C++分析——特殊容器STL使用

雨点打透心脏的1/2处 2022-05-28 13:49 187阅读 0赞

*  排序容器sort
    
     *  使用默认排序比较
     *  使用自定义比较器比较
 *  乱序容器random\_shuffle

# 排序容器sort #

排序容器sort，将数组的元素从大到小或从小到达排序；  
乱序容器random\_shuffle，将数组的元素的顺序随机打乱，需要配合随机因子。

头文件：\#include

## 使用默认排序比较 ##

std::vector<int> Value;
        Value.push_back(1);
        Value.push_back(3);
        Value.push_back(5);
        Value.push_back(7);
        Value.push_back(9);
        Value.push_back(6);
        Value.push_back(9);
        Value.push_back(2);
        Value.push_back(4);
    
    //默认从小到大排序
        std::sort(Value.begin(), Value.end());
        Show_info(Value);
    
        cout << "Next " << endl;
    
    //加入比较器，比较类型为int值，从大到小排序
        std::sort(Value.begin(), Value.end(),std::greater<int>());
        Show_info(Value);

执行结果

$ ./project.o 
    CSystem is called.
    
    int vertor info is 1
    int vertor info is 2
    int vertor info is 3
    int vertor info is 4
    int vertor info is 5
    int vertor info is 6
    int vertor info is 7
    int vertor info is 9
    int vertor info is 9
    Next 
    int vertor info is 9
    int vertor info is 9
    int vertor info is 7
    int vertor info is 6
    int vertor info is 5
    int vertor info is 4
    int vertor info is 3
    int vertor info is 2
    int vertor info is 1

## 使用自定义比较器比较 ##

通常，比较的类型不仅仅是值层面的比较，还需要类的比较，比较后将他们重新排序。这时候需定义类的比较器，并重载“<”和“>”号。

定义一个类，类成员函数有ID值和数值

class CInfo
    {
    public:
        CInfo():index(0),m_number(0){}
        CInfo(int index_value,int number_value):index(index_value),m_number(number_value){}
        ~CInfo(){index = 0;m_number = 0;}
    
        void set_index(int value){ index = value;}
        int get_index(){
       return index;}
    
        void set_number(int value){ m_number = value;}
        int get_number(){
       return m_number;}
    
        //定义比较器比较大的值
        static bool Cmp(CInfo &origin_value,CInfo &cmp_calue)
        {
            return origin_value > cmp_calue;
        }
    
        //重载<
        bool operator<(CInfo &value)
        {
            return this->m_number < value.m_number;
        }
        //重载>
        bool operator>(CInfo &value)
        {
            return this->m_number > value.m_number;
        }
        //重载os输出 <<
        friend std::ostream& operator<< (std::ostream &os,CInfo &out)
        {
            os<< "Info index is " << out.index << " number is "<< out.m_number <<std::endl;
            return os;
        }
        //重载os输出 <<
        friend std::ostream& operator<<(std::ostream &os,std::vector<CInfo> &out)
        {
            std::vector<CInfo>::iterator iter = out.begin();
    
            while(iter != out.end())
            {
                os << *iter;
                iter++;
            }
    
            return os;
        }
    
    private:
        int index;
        int m_number;
    };

以及定义这个类的容器  
std::vector Class\_Value;

容器里面的值是在不同时期加进去的，里面顺序数值随机，此时需要根据类中成员变量m\_number的值，对这个类的容器里面的值进行从大到小或从小到大排序。

测试源码：

srand((unsigned)time(NULL));
        std::vector<CInfo> Class_Value;
    
        for(int i = 0;i < 10;i++)
        {
            //生成随机数
            CInfo info(rand()%10, rand()%100);
            Class_Value.push_back(info);
        }
    
        cout << Class_Value << endl;
    
        cout << "Sorting after ... " << endl;
        std::sort(Class_Value.begin(), Class_Value.end(),CInfo::Cmp);
        cout << Class_Value << endl;

执行结果

$ ./project.o 
    CSystem is called.
    Info index is 9 number is 56
    Info index is 6 number is 14
    Info index is 3 number is 97
    Info index is 8 number is 97
    Info index is 8 number is 67
    Info index is 5 number is 87
    Info index is 5 number is 51
    Info index is 7 number is 64
    Info index is 8 number is 67
    Info index is 3 number is 92
    
    "Sorting after ...
    Info index is 3 number is 97
    Info index is 8 number is 97
    Info index is 3 number is 92
    Info index is 5 number is 87
    Info index is 8 number is 67
    Info index is 8 number is 67
    Info index is 7 number is 64
    Info index is 9 number is 56
    Info index is 5 number is 51
    Info index is 6 number is 14

# 乱序容器random\_shuffle #

乱序容器是将容器内的成员随机打乱顺序，顺序的随机程度由随机种子决定。  
头文件：\#include

测试源码：

//依据时间生成随机种子
        srand((unsigned)time(NULL));
    
        std::vector<int> Class_Value;
    
        for (int i = 0; i < 10; i++)
        {
            Class_Value.push_back(i);
        }
    
        cout << "random shuffle after ... " << endl;
        random_shuffle(Class_Value.begin(), Class_Value.end());
    
        std::vector<int>::iterator iter = Class_Value.begin();
    
        while (iter != Class_Value.end())
        {
            cout << "vector number is " << *iter << endl;
    
            iter++;
        }

执行结果

$ ./project.o 
    CSystem is called.
    random shuffle after ... 
    vector number is 8
    vector number is 4
    vector number is 6
    vector number is 2
    vector number is 5
    vector number is 9
    vector number is 3
    vector number is 7
    vector number is 0
    vector number is 1