Question

我只是在学习C ++类，并且正在尝试比较和排序矢量值（时间早于其他时间），而其他一切都有效，而矢量中的最后一个值不会被打印出来。我猜测它与我的主要功能中的for循环有关，但我不能自己解决。

感谢您的帮助！

的main.cpp

#include <iostream>
#include "Time.h"
#include <vector>
#include <algorithm>

int main() {
    std::cout << "Please enter hour, minute, second: ";
    int hour, minute, second;
    std::cin >> hour >> minute >> second;
    Time now(hour, minute, second);
        //random time values
    Time now1(13,1,45);
    Time now2(23,47,12);
    Time now3(1,8,8);
    Time now4(19,4,13);

    std::vector<Time> times;
    times.push_back(now1);
    times.push_back(now);
    times.push_back(now2);
    times.push_back(now3);
    times.push_back(now4);
    sort(times.begin(), times.end(), IsEarlierThan);

    for(unsigned int i = 0; i < times.size(); i++){
        //std::cout << times[i] << std::endl;
        times[i].PrintAmPm();
    }

    return 0;
}

Time.cpp

#include <iostream>
#include <string>
#include "Time.h"

Time::Time() {
    hour = 0;
    minute = 0;
    second = 0;
}

Time::Time(int theHour, int theMinute, int theSecond){
    hour = theHour;
    minute = theMinute;
    second = theSecond;
}

int Time::getHour() const {
    return hour;
}

int Time::getMinute() const {
    return minute;
}

int Time::getSecond() const{
    return second;
}

void Time::PrintAmPm() const {
    int hour1;
    std::string amOrPm;
    if ((hour >= 0) && (hour <= 11))
        amOrPm = "am";
    else
        amOrPm = "pm";

    if ((hour > 12) && (hour <= 23))
        hour1 = hour - 12;
    if (hour == 0)
        hour1 = hour + 12;
    if ((hour > 0) && (hour <= 12))
        hour1 = hour;

    if ((minute < 10) && (second >=10))
        std::cout << hour1 << ":0" << minute << ":" << second << amOrPm << std::endl;
    if ((minute < 10) && (second < 10))
         std::cout << hour1 << ":0" << minute << ":0" << second << amOrPm << std::endl;
    if ((minute >= 10) && (second < 10))
        std::cout << hour1 << ":" << minute << ":0" << second << amOrPm << std::endl;
}

bool IsEarlierThan(const Time& t1, const Time& t2){
    if (t1.getHour() < t2.getHour())
        return true;
    if ((t1.getHour() == t2.getHour()) && (t1.getMinute() < t2.getMinute()))
        return true;
    if ((t1.getHour() == t2.getHour()) && (t1.getMinute() == t2.getMinute()) 
            && (t1.getSecond() < t2.getSecond()))
        return true;
    else
        return false;
}

时间。 ħ

class Time {
public:
    Time();
    Time(int theHour, int theMinute, int theSecond);

    int getHour() const;
    int getMinute() const;
    int getSecond() const;

    void PrintAmPm() const;

private:
    int hour;
    int minute;
    int second;
};

bool IsEarlierThan(const Time& t1, const Time& t2);

Answer 1

您没有看到其中一个输出，因为您的测试从未在minutes >= 10和second >= 10时打印。

if ((minute < 10) && (second >=10))
if ((minute < 10) && (second < 10))
if ((minute >= 10) && (second < 10))
// None of these handle minute >= 10 && second >= 10!

now2有两位数分钟和秒，因此您的打印方法无效。

真的，这里正确的解决方案是只需使用cout std::cout << std::setfill('0') << hour1 << ':' << std::setw(2) << minute << ':' << std::setw(2) << second << amOrPm << std::endl;替换这些测试，使用std::setfill和std::setw来对齐输出，而无需手动/有条件地归零。

minute

无需检查second / cout的范围，您只是无条件告诉0应使用char填充，并设置所需的宽度以填充to（需要每次都设置，因为输出const m = moment.tz("01/01/2019 5:30pm", "MM/DD/YYYY h:mma", true, "invalid timezone"); m.isValid(); //true会重置宽度）。

对于循环不在C ++中打印最后一个向量值

1 个答案: