第八周项目二-Time类中的运算符重载

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实现Time类中的运算符重载

class CTime{private:    unsigned short int hour;    // 时    unsigned short int minute;  // 分    unsigned short int second;  // 秒public:    CTime(int h=0,int m=0,int s=0);    void setTime(int h,int m,int s);    void display();    //二目的比较运算符重载    bool operator > (CTime &t);    bool operator < (CTime &t);    bool operator >= (CTime &t);    bool operator <= (CTime &t);    bool operator == (CTime &t);    bool operator != (CTime &t);    //二目的加减运算符的重载    //返回t规定的时、分、秒后的时间    //例t1(8,20,25),t2(11,20,50)，t1+t2为19:41:15    CTime operator+(CTime &t);    CTime operator-(CTime &t);//对照+理解    CTime operator+(int s);//返回s秒后的时间    CTime operator-(int s);//返回s秒前的时间    //二目赋值运算符的重载    CTime operator+=(CTime &c);    CTime operator-=(CTime &c);    CTime operator+=(int s);//返回s秒后的时间    CTime operator-=(int s);//返回s秒前的时间};

提示一：并不是所有的比较运算重载函数都很复杂

//比较运算返回的是比较结果，是bool型的true或false//可以直接使用已经重载了的运算实现新运算，例如果已经实现了 > ，则实现 <= 就可以很方便了……bool CTime::operator <= (CTime &t) // 判断时间t1<=t2{    if (*this > t) return false;    return true;}

提示二：并不是所有复合赋值运算重载函数都需要很复杂

//可以直接使用已经重载了的加减运算实现//这种赋值, 例如 t1+=20，直接改变当前对象的值，所以在运算完成后，将*this作为返回值CTime CTime::operator+=(CTime &c){    *this=*this+c;    return *this;}

提示三：请自行编制用于测试的main()函数，有些结果不必依赖display()函数，提倡用单步执行查看结果

#include <iostream>using namespace std;class CTime{private:    unsigned short int hour;    // 时    unsigned short int minute;  // 分    unsigned short int second;  // 秒public:    CTime(int h=0,int m=0,int s=0);    void setTime(int h,int m,int s);    void display();    //二目的比较运算符重载    bool operator > (CTime &t);    bool operator < (CTime &t);    bool operator >= (CTime &t);    bool operator <= (CTime &t);    bool operator == (CTime &t);    bool operator != (CTime &t);    //二目的加减运算符的重载    //返回t规定的时、分、秒后的时间    //例t1(8,20,25),t2(11,20,50)，t1+t2为19:41:15    CTime operator+(CTime &t);    CTime operator-(CTime &t);//对照+理解    CTime operator+(int s);//返回s秒后的时间    CTime operator-(int s);//返回s秒前的时间    //二目赋值运算符的重载    CTime operator+=(CTime &c);    CTime operator-=(CTime &c);    CTime operator+=(int s);//返回s秒后的时间    CTime operator-=(int s);//返回s秒前的时间};CTime::CTime(int h,int m,int s){    hour=h;    minute=m;    second=s;}void CTime::setTime(int h,int m,int s){    hour=h;    minute=m;    second=s;}void CTime::display(){    cout<<hour<<":"<<minute<<":"<<second<<endl;}bool CTime::operator > (CTime &t){    int s1,s2;    s1=hour*3600+minute*60+second;    s2=t.hour*3600+t.minute*60+t.second;    if (s1>s2) return true;    else        return false;}bool CTime::operator < (CTime &t){    int s1,s2;    s1=hour*3600+minute*60+second;    s2=t.hour*3600+t.minute*60+t.second;    if (s1<s2) return true;    else        return false;}bool CTime::operator >= (CTime &t){    if (*this > t) return true;    return false;}bool CTime::operator <= (CTime &t){    if (*this > t) return false;    return true;}bool CTime::operator == (CTime &t){    int s1,s2;    s1=hour*3600+minute*60+second;    s2=t.hour*3600+t.minute*60+t.second;    if (s1==s2) return true;    else        return false;}bool CTime::operator != (CTime &t){    int s1,s2;    s1=hour*3600+minute*60+second;    s2=t.hour*3600+t.minute*60+t.second;    if (s1!=s2) return true;    else        return false;}CTime CTime::operator+(CTime &t){    int s;    s=t.hour*3600+t.minute*60+t.second;    while (s--)    {        second++;        if (second>60)        {            minute++;            second=1;        }        if (minute>60)        {            hour++;            minute=1;        }    }    CTime a(hour,minute,second);    return a;}CTime CTime::operator-(CTime &t){    int s;    s=t.hour*3600+t.minute*60+t.second;    while (s--)    {        second--;        if (second<0)        {            minute--;            second=60;        }        if (minute<0)        {            hour--;            minute=60;        }    }    CTime a(hour,minute,second);    return a;}CTime CTime::operator+(int s){    while (s--)    {        second++;        if (second>60)        {            minute++;            second=1;        }        if (minute>60)        {            hour++;            minute=1;        }    }    CTime a(hour,minute,second);    return a;}CTime CTime::operator-(int s){    while (s--)    {        second--;        if (second<0)        {            minute--;            second=60;        }        if (minute<0)        {            hour--;            minute=60;        }    }    CTime a(hour,minute,second);    return a;}CTime CTime::operator+=(CTime &c){    *this=*this+c;    return *this;}CTime CTime::operator-=(CTime &c){    *this=*this-c;    return *this;}CTime CTime::operator+=(int s){    *this=*this+s;    return *this;}CTime CTime::operator-=(int s){    *this=*this-s;    return *this;}int main(){    CTime t1(8,20,25),t2(11,20,50),t;    cout<<"t1为：";    t1.display();    cout<<"t2为：";    t2.display();    cout<<"下面比较两个时间大小：\n";    if (t1>t2) cout<<"t1>t2"<<endl;    if (t1<t2) cout<<"t1<t2"<<endl;    if (t1==t2) cout<<"t1＝t2"<<endl;    if (t1!=t2) cout<<"t1≠t2"<<endl;    if (t1>=t2) cout<<"t1≥t2"<<endl;    if (t1<=t2) cout<<"t1≤t2"<<endl;    cout<<endl;}

运行结果;

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