第6周项目4-静态成员应用

来源：互联网发布：react.js阮一峰编辑：程序博客网时间：2024/06/07 01:50

参考答案：

#include <iostream>using namespace std;class Time{public:    Time(int=0,int=0,int=0);    void show_time( ); //根据is_24和from0，输出适合形式的时间:23:5/8:23:5 pm/08:23:05 pm    void add_seconds(int); //增加n秒钟    void add_minutes(int); //增加n分钟    void add_hours(int); //增加n小时    static void change24();  //改变静态成员is_24，在和时制之间转换    static void changefrom0();   //改变静态成员from0，转换是否前导private:    static bool is_24; //为true时，小时制，如:23:5；为flase，小时制，显示为:23:5 pm    static bool from0; //为true时，前导，:23:5显示为:23:05    int hour;    int minute;    int sec;};bool Time::is_24=true;bool Time::from0=false;Time::Time(int h,int m,int s): hour(h), minute(m), sec(s){}void Time::show_time( ){    int h=(is_24)?hour:hour%12;  //这种写法比下面注释掉的写法更简洁    //if(is_24)    //  h=hour;    //else    //  h=hour%12;    if (h<10&&from0) cout<<'0';    cout<<h<<':';    if(minute<10&&from0) cout<<'0';    cout<<minute<<':';    if(sec<10&&from0) cout<<'0';    cout<<sec;    if(!is_24)        cout<<((hour>12)? " pm":" am");        //if (hour>12)        //  cout<<" pm";        //else        //  cout<<" am";    cout<<endl;}void Time::add_seconds(int n) //增加n秒钟{    sec+=n;    if (sec>59)    {        add_minutes(sec/60);        sec%=60;    }}void Time::add_minutes(int n) //增加n分钟{    minute+=n;    if (minute>59)    {        add_hours(minute/60);        minute%=60;    }}void Time::add_hours(int n) //增加n小时{    hour+=n;    if (hour>23)        hour%=24;}void Time::change24(){    is_24=!is_24;}void Time::changefrom0(){    from0=!from0;}int main( ){    Time t1(23,14,25),t2(8,45,6);    cout<<"24时制, 无规格："<<endl;    cout<<"    t1是：";    t1.show_time();    cout<<"    t2是：";    t2.show_time();    t1.add_hours(10);    t2.add_hours(10);    Time::changefrom0(); //注意此处调用静态成员    cout<<"10小时后, 规格输出："<<endl;    cout<<"    t1是：";    t1.show_time();    cout<<"    t2是：";    t2.show_time();    t1.change24();    cout<<" 带提示 换格式输出："<<endl;    cout<<"    t1是：";    t1.show_time();    cout<<"    t2是：";    t2.show_time();    return 0;}

我的答案：

#include <iostream>using namespace std;class Time{public:    Time(int=0,int=0,int=0);    void show_time( ); //根据is_24和from0，输出适合形式-20:23:5/8:23:5 pm/08:23:05 pm    void add_seconds(int); //增加n秒钟    void add_minutes(int); //增加n分钟    void add_hours(int); //增加n小时    static void change24();  //改变静态成员is_24，在12和24时制之间转换    static void changefrom0();   //改变静态成员from0，切换是否前导0 private:    static bool is_24; //为true时，24小时制，如20:23:5；为flase，12小时制，显示为8:23:5 pm    static bool from0; //为true时，前导0，8:23:5显示为08:23:05    int hour;    int minute;    int sec;};bool Time::is_24=true;bool Time::from0=false;//下面写出静态成员的初始化及各成员函数的定义……Time::Time(int h,int m,int s){    hour=h;    minute=m;    sec=s;}void Time::add_hours(int h){    hour+=h;    hour>24?(hour%24):hour;}void Time::add_minutes(int m){    minute+=m;    if(minute>59)    {        minute%=60;        add_hours(minute/60);    }}void Time::add_seconds(int s){    sec+=s;    if(sec>59)    {        sec%=60;        add_minutes(sec/60);    }}void Time::show_time( ){    if(hour<10&&from0)cout<<'0';    cout<<hour<<':';    if(minute<10&&from0)cout<<'0';    cout<<minute<<':';    if(sec<10&&from0)cout<<'0';    cout<<sec<<endl;    if(!is_24)      cout<<((hour>12)? " pm":" am");}void Time::change24(){    is_24=!is_24;}void Time::changefrom0(){    from0=!from0;}int main( ){    Time t1(23,14,25),t2(8,45,6);        cout<<"24时制, 不前导："<<endl;    cout<<"    t1是：";    t1.show_time();    cout<<"    t2是：";    t2.show_time();    t1.add_hours(10);    t2.add_hours(10);    Time::changefrom0(); //注意此处调用静态成员    cout<<"10小时后, 切换是否前导："<<endl;    cout<<"    t1是：";    t1.show_time();    cout<<"    t2是：";    t2.show_time();    t1.change24();    cout<<"换一种制式："<<endl;    cout<<"    t1是：";    t1.show_time();    cout<<"    t2是：";    t2.show_time();    return 0;}

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