C ++如何获取class中的名称，使其成为基于我输入时间的排名系统

Question

我可以将我的对象存储在一个 class 变量中以便打印排名名称吗？

问题是编写一个程序，询问五名跑步者的姓名以及他们每人完成一场比赛所花费的时间。该程序应显示谁排在第一、第二和第三位。次数只接受正数。

我应该做哪些修改？

#include <iostream>

using namespace std;

class runner{
    public:
        char name[50];
        float time;
        
        void input(){
            
            cout <<"\n Enter the name: ";
            cin>> name;
            cout <<"\n Enter the time taken to finish the race (mins): ";
            cin>> time;
        }
        
        
        
};

int main(){
    
    runner runners[5];
    for(int i =0;i<5; i++){
        
        runners[i].input();
    }
    
    int i,first, second, third, fourth, fifth;
    fifth = fourth = third = first = second = INT_MIN;
    char firstname, secondname, thirdname, fourthname, fifthname;
    for(int i =0;i<5; i++){
        if(runners[i].time>first){
            fifth = fourth; 
            fourth = third; 
            third = second; 
            second = first; 
            first = runners[i].time;    
            
        }
        else if(runners[i].time> second){
            fifth = fourth; 
            fourth = third; 
            third = second; 
            second = runners[i].time; 
        }
        else if(runners[i].time>third){
            fifth = fourth; 
            fourth = third; 
            third = runners[i].time; 
            
        }
        else if(runners[i].time>fourth){
            fifth = fourth; 
            fourth = runners[i].time; 
            
        }
        else if(runners[i].time>fifth){
            fifth = runners[i].time; 
        
        }
    }

    
    cout << first <<","<< second <<","<< third <<","<< fourth<< ","<< fifth<<endl;
    
    return 0;
}

Answer 1

是的，你可以。

您可以编写自定义比较函数：

class runner
{
public:
    std::string name; // why not std::string?
    float time;
        
    void input()
    {    
        std::cout <<"\n Enter the name: ";
        std::cin >> name;
        std::cout <<"\n Enter the time taken to finish the race (mins): ";
        std::cin >> time;
    }
};

bool cmp (const runner &lhs, const runner &rhs)
{
    return lhs.time < rhs.time;
}
std::ostream& operator<< (std::ostream& out, const runner& run)
{
    out << run.name << ' ' << run.time;
}
int main()
{
    runner runners[5];
    for(int i =0;i<5; i++)
    {
        runners[i].input();
    }
    std::sort(runners, runners + 5, cmp);

   for(int i {4}; i >= 0; --i)
   {
       std::cout << runners[i] << ' ' << i << ',';
   }
}

或者您可以重载 < 运算符：

class runner
{
public:
    std::string name; 
    float time;
        
    void input()
    {    
        std::cout <<"\n Enter the name: ";
        std::cin >> name;
        std::cout <<"\n Enter the time taken to finish the race (mins): ";
        std::cin >> time;
    }
};
bool operator< (const runner &lhs, const runner &rhs)
{
    return lhs.time < rhs.time;
}
int main()
{
    runner runners[5];
    for(int i =0;i<5; i++)
    {
        runners[i].input();
    }
    std::sort(runners, runners + 5);
    for(int i {4}; i >= 0; --i)
    {
        std::cout << runners[i] << ' ' << i << ',';
    }
}

Answer 2

您可以使用 std::multiset 简化您的程序，如图 below:

#include <iostream>
#include <string>
#include <set> 

//using namespace std; //don't use this

class runner{
    public:
        std::string name; //use string instead of array of char
        float time;
        
        void input(){
            
            std::cout <<"\n Enter the name: ";
            std::cin>> name;
            std::cout <<"\n Enter the time taken to finish the race (mins): ";
            std::cin>> time;
        }
        //overload operator< since we are using std::set
        bool operator<( const runner &r ) const
        {
            return ( time < r.time );
        }
};

int main(){
    
    std::multiset<runner> runners; //use multiset instead of array
    for(int i =0;i<5; i++){
        
        runner tempRunner;
        tempRunner.input();
        
        runners.insert(tempRunner);
    }
    
    int i = 0;
    //print out the details as asked in the assignment question. You can adjust 
//the output according to your needs for example if you want to display only first 
//3 position details or what if all the first three persons in the multiset have the same timing
    for(const runner &tempRunner: runners)
    {
        std::cout<<tempRunner.name <<" came: "<<i+1<<std::endl;
        ++i;
    }
    return 0;
}

注意使用multiset而不是set，因为不止一个跑步者可以有相同的时间。

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