C++ Primer Plus 第11章习题4 答案

最新推荐文章于 2025-12-22 20:10:38 发布

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本文介绍了一个简单的C++时间类的实现及其各种运算符重载方法，包括加法、减法和乘法等。此外，还展示了如何通过友元函数实现这些操作，并提供了输出时间格式的方法。

#ifndef MYTIME3_H_
#define MYTIME3_H_

#include <iostream>

class Time
{
private:
	int hours;
	int minutes;

public:
	Time();
	Time(int h, int m = 0);
	void AddMin(int m);
	void AddHr(int h);
	void Reset(int h = 0, int m = 0);

	friend Time& operator+(const Time& s, const Time& ano);
	friend Time& operator-(const Time& s, const Time& ano);
	friend Time& operator*(const Time& s, double n);
	
	friend Time operator*(double m, const Time& t)
	{
		return t * m;
	}
	friend std::ostream& operator<<(std::ostream& os, const Time& t);
};


#endif




#include "ex11-2.h"

Time::Time()
{
	hours = 0;
	minutes = 0;
}

Time::Time(int h, int m)
{
	hours = h;
	minutes = m;
}

void Time::AddMin(int m)
{
	minutes += m;
	hours += minutes / 60;
	minutes %= 60;
}




void Time::AddHr(int h)
{
	hours += h;
}


void Time::Reset(int h, int m)
{
	hours = h;
	minutes = m;
}

Time& operator+(const Time& s, const Time& ano)
{
	Time sum;
	sum.minutes = s.minutes + ano.minutes;
	sum.hours = s.hours + ano.hours + sum.minutes / 60;
	sum.minutes %= 60;
	return sum;
}

Time& operator-(const Time& s, const Time& ano)
{
	Time diff;
	int tot1, tot2;
	tot1 = s.minutes + s.hours * 60;
	tot2 = ano.minutes + ano.hours * 60;
	diff.minutes = (tot1 - tot2) % 60;
	diff.hours = (tot1 - tot2) / 60;
	return diff;
}

Time& operator*(const Time& s, double n)
{
	Time temp;
	long totalminutes;
	totalminutes = s.hours * n * 60 + s.minutes * n;
	temp.minutes = totalminutes % 60;
	temp.hours = totalminutes / 60;
	return temp;
}

std::ostream& operator<<(std::ostream& os, const Time& t)
{
	os << t.hours << " hours " << t.minutes << " minutes ";
	return os;
}



#include <iostream>
#include "ex11-2.h"

int main()
{
	Time aida(3, 35);
	Time tosca(2, 48);
	Time temp;

	std::cout << "aida and tosca: " << std::endl;
	std::cout << aida << "; " << tosca << std::endl;
	temp = aida + tosca;
	std::cout << "aida + tosca: " << temp << std::endl;
	temp = aida * 1.17;

	std::cout << "aida * 1.17: " << temp << std::endl;
	std::cout << "10.0 * tosca: " << 10.0 * tosca << std::endl;


	return 0;
}