新手遇一个不懂的问题

2014-06-29 06:02:28 176 阅读 AI 写同款 · GEO 优化AI 选题数据监测一键分发 ›

保姆级教程：用PyBullet和Stable-Baselines3搞定你的第一个机器人强化学习项目本文提供了一份详细的PyBullet和Stable-Baselines3教程，帮助开发者快速上手机器人强化学习项目。通过环境配置、自定义Gym环境构建、PPO算法参数优化及模型部署的全流程解析，读者将掌握从零开始训练四足机器人 locomotion 任务的完整技术方案。阅读详情

来自c++ primer plus 第14章，程序清单14.2，代码如下

#ifndef STUDENTC_H_

#define STUDENTC_H_

#include <iostream>

#include <valarray>

#include <string>



using namespace std;



class Student

{

private:

	string name;

	typedef valarray<double> ArrayDb;

	ArrayDb scores;

	ostream & arr_out(ostream & os)const;

public:

	Student():name("null student"),scores(){}

	Student(const string &s):name(s),scores(){}

	explicit Student(int n):name("nully"),scores(n){}

	Student(const string &s,int n):name(s),scores(n){}

	Student(const string &s,const ArrayDb & a):name(s),scores(a){}

	Student(const char *str,const double *pd,int n):name(str),scores(pd,n){}

	~Student(){}

	double Average()const;

	const string & Name()const;

	double & operator[](int i );

	double operator[](int i) const;

	friend istream & operator>>(istream &is,Student &stu);

	friend ostream & operator<<(ostream &os,Student &stu);

	friend istream & getline(istream &is,Student &stu);

};



#endif

#include "student.h"



double Student::Average()const

{

	if(scores.size()>0)

		return scores.sum() / scores.size();

	else 

		return 0;

}



const string & Student::Name()const

{

	return name;

}



double & Student::operator[](int i)

{

	return scores[i];

}



double Student::operator[](int i)const

{

	return scores[i];

}



ostream & Student::arr_out(ostream & os)const

{

	int i;

	int lim = scores.size();

	if(lim > 0)

	{

		for(i = 0;i > lim;i++)

		{

			os << scores[i] << " ";

			if(i % 5 == 4)

				os << endl;

		}

	

		if(i % 5 != 0)

			os << endl;

	}

	else 

		os << "empty array!";

	return os;

}



istream & operator>>(istream &is,Student &stu)

{

	is >> stu.name;

	return is;

}



istream & getline(istream &is,Student &stu)

{

	getline(is,stu.name);

	return is;

}



ostream & operator<<(ostream &os,Student &stu)

{

	os << "scores for " << stu.name << ":\n";

	stu.arr_out(os);

	return os;

}

#include <iostream>

#include "student.h"



using namespace std;



void set(Student &sa,int n);



const int pupils = 3;

const int quizzes = 5;



int main()

{

	Student ada[pupils] = {Student(quizzes),Student(quizzes),Student(quizzes)};

	int i;

	for(i = 0;i < pupils;++i)

		set(ada[i],quizzes);

	cout << "\nStudent list:\n";

	for(i = 0;i < pupils;++i)

		cout << ada[i].Name() << endl;

	cout << "\nResult:";

	for(i = 0;i < pupils;++i)

	{

		cout << endl << ada[i];

		cout << "average: " << ada[i].Average() << endl;

	}

	cout << "Done!\n";

	

	return 0;

}



void set(Student &sa,int n)

{

	cout << "Please enter the student's name: ";

	getline(cin,sa);

	cout << "Please enter " << n << " quiz scores:\n";

	for(int i = 0;i < n;i++)

		cin >> sa[i];

	while(cin.get() != '\n')

		continue;

}

main函数里面倒数第三行代码不能理解，也就是set函数中：
for(int i = 0;i < n;i++)
cin >> sa[i];
根据功能，这行是输入每个对象对应的5次分数。
可是为什么cin >> sa[i],就是输入分数呢？sa是一个student对象啊，怎么能当做对象的socres成员接收数据呢？而且>>重载了用作接收name成员，所以我就百思不得解了！
期待给我一个指点，帮我解惑，谢谢！

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