运算符的重载

用户8247415

发布于 2021-04-13 16:14:39

4940

发布于 2021-04-13 16:14:39

文章被收录于专栏：网页前端

c++内类的运用

1.计算时间

#include 
using namespace std;
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);
    Time Sum(const Time& t) const;
    void Show() const;
};

Time::Time()
{
    hours = 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 Time::Sum(const Time& t) const
{
    Time sum;
    sum.minutes = minutes + t.minutes;
    sum.hours = hours + t.hours + sum.minutes / 60;
    sum.minutes %= 60;
    return sum;
}

void Time::Show() const
{
    std::cout << hours << " hours, " << minutes << " minutes";
}


int main()
{
    using std::cout;
    using std::endl;
    Time planning;
    Time coding(2, 40);
    Time fixing(5, 55);
    Time total;

    cout << "planning time = ";
    planning.Show();
    cout << endl;

    cout << "coding time = ";
    coding.Show();
    cout << endl;

    cout << "fixing time = ";
    fixing.Show();
    cout << endl;

    total = coding.Sum(fixing);
    cout << "coding.Sum(fixing) = ";
    total.Show();
    cout << endl;

    return 0;
}

这是一串简单的类代码，比较重要的是sum()函数，注意到了参数是引用但是返回类型不是引用。将参数声明作为引用的目的只是为了提高效率，传递引用速度更快，使用的内存更少。看一下输出内容QAQ

planning time = 0 hours, 0 minutes
coding time = 2 hours, 40 minutes
fixing time = 5 hours, 55 minutes
coding.Sum(fixing) = 8 hours, 35 minutes

接下来我们要在类里面添加加法运算符“+” 我们只修改主函数和sum()函数声明，其他的都是一样的。

include <iostream>
using namespace std;
int main()
{
    using std::cout;
    using std::endl;
    Time planning;
    Time coding(2, 40);
    Time fixing(5, 55);
    Time total;

    cout << "planning time = ";
    planning.Show();
    cout << endl;

    cout << "coding time = ";
    coding.Show();
    cout << endl;

    cout << "fixing time = ";
    fixing.Show();
    cout << endl;

    total = coding + fixing;
    // operator notation
    cout << "coding + fixing = ";
    total.Show();
    cout << endl;

    Time morefixing(3, 28);
    cout << "more fixing time = ";
    morefixing.Show();
    cout << endl;
    total = morefixing.operator+(total);
    // function notation
    cout << "morefixing.operator+(total) = ";
    total.Show();
    cout << endl;

    return 0;
}

operator+()也是由Time对象调用的，第二个Time的对象作为参数，斌且返回一个Time对象。因此可以用sum()方法调用。运算符重载非常好用，但是也有许多限制，下一章来叙述。

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原始发表：2021/03/23 ，如有侵权请联系 cloudcommunity@tencent.com 删除

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