Question

我终于让我的任务几乎完成了，但是现在我在编译时遇到了一组全新的错误。

#include <iostream>

using namespace std;

class clockType
{
      friend ostream& operator<<(ostream&, const clockType&);
      friend istream& operator>>(istream&, clockType&);
public:
      void setTime (int hours, int minutes, int seconds);
      void getTime (int& hours, int& minutes, int& seconds) const;     
      clockType operator++();
      bool operator==(const clockType& otherClock) const;
      bool operator!= (const clockType& otherClock) const;
      bool operator<=(const clockType& otherClock) const;
      bool operator<(const clockType& otherClock) const;
      bool operator>=(const clockType& otherClock) const;
      bool operator>(const clockType& otherClock) const;
      clockType ();
      clockType (int hours = 0, int minutes = 0, int seconds = 0);
private:
        int hr;
        int min;
        int sec;
};
clockType clockType::operator++()
{
          sec++;
          if (sec > 59)
          {
              sec = 0;
              min++;
              if (min > 59)
              {
                      min = 0;
                      hr++;
                      if (hr > 23)
                      hr = 0;
              }
          }
          return *this;
}
bool clockType::operator==(const clockType& otherClock) const
{
     return (hr == otherClock.hr && min == otherClock.min && sec == otherClock.sec);
}
bool clockType::operator<=(const clockType& otherClock) const
{
     return ((hr < otherClock.hr) || (hr == otherClock.hr && min < otherClock.min) || (hr == otherClock.hr && min == otherClock.min && sec <= otherClock.sec));
}
bool clockType::operator!=(const clockType& otherClock) const
{
          return (hr != otherClock.hr || min != otherClock.min || sec != otherClock.sec);
}
bool clockType::operator<(const clockType& otherClock) const
{
     return ((hr < otherClock.hr) || (hr == otherClock.hr && min < otherClock.min) || (hr == otherClock.hr && min == otherClock.min && sec < otherClock.sec));
}
bool clockType::operator>=(const clockType& otherClock) const
{
     return ((hr > otherClock.hr) || (hr == otherClock.hr && min > otherClock.min) || (hr == otherClock.hr && min == otherClock.min && sec >= otherClock.sec));
}
bool clockType::operator>(const clockType& otherClock) const
{
     return ((hr > otherClock.hr) || (hr == otherClock.hr && min > otherClock.min) || (hr == otherClock.hr && min == otherClock.min && sec > otherClock.sec));
}

void clockType::setTime(int hours, int minutes, int seconds)
{
     if (0 <= hours && hours < 24)
     hr = hours;
     else
     hr = 0;
     if (0 <= minutes && minutes < 60)
     min = minutes;
     else
     min = 0;
     if (0 <= seconds && seconds < 60)
     sec = seconds;
     else
     sec = 0;
}
void clockType::getTime(int& hours, int& minutes, int& seconds)const
{
     hours = hr;
     minutes = min;
     seconds = sec;
}
clockType::clockType(int hours, int minutes, int seconds)
{
 setTime(hours, minutes, seconds);
}
ostream& operator<<(ostream& osObject, const clockType& timeOut)
{
         if (timeOut.hr < 10)
         osObject << '0';
         osObject << timeOut.hr << ':';
         if (timeOut.min < 10)
         osObject << '0';
         osObject << timeOut.min << ':';
         if (timeOut.sec < 10)
         osObject << '0';
         osObject << timeOut.sec << ':';
         return osObject;
}
istream& operator>>(istream& is, clockType& timeIn)
{
         char ch;
         is >> timeIn.hr;
         if (timeIn.hr < 0 || timeIn.hr >=24)
         timeIn.hr = 0;
         is.get(ch);
         is >> timeIn.min;
         if (timeIn.min < 0 || timeIn.min >= 60)
         timeIn.min = 0;
         is.get(ch);
         is >> timeIn.sec;
         if (timeIn.sec < 0 || timeIn.sec >= 60)
         timeIn.sec = 0;
         return is;
}
int main() 
{ 
   clockType  myClock(4, 9, 22);
   clockType yourClock ();

   cout << "myClock = " << myClock << endl;
   cout << "yourClock = " << yourClock << endl;
   cout << "enter the time in form " << "hr:min:sec ";
   cin >> myClock;
   cout << endl;
   cout << "The new time of myClock = " << myClock << endl; 
   ++myClock;
   cout << "After incrementing the time, " << "myClock = " << myClock << endl;
   yourClock.setTime(15, 20, 25);
   cout << "After setting the time, " << "yourClock = " << yourClock << endl;
   if (myClock == yourClock)
   cout << "The times of myClock and " << "yourClock are equal." << yourClock << endl;
   else
   cout << "The times of myClock and " << "yourClock are not equal." << endl;
   if (myClock <= yourClock)
   cout << "The time of myClock is " << "less than or equal to " << endl << "the time of yourClock " << endl;
   else
   cout << "The time of myClock is " << "greater than the time of " << "yourClock." << endl;
   return 0;
}

我得到的错误是：

在函数main（）中;
调用重载'clockType（）'是不明确的候选者是：clockType :: clockTYpe（int，int，int）clockType :: clockType（）。

我不确定这对我有什么要求或错误到底是什么。

Answer 1

如果没有参数，你的构造函数都是候选者。

clockType();                                                 // takes zero parameters.
clockType (int hours = 0, int minutes = 0, int seconds = 0); // can take zero parameters.

// Thus the compiler does not know whaich one to call.

这也不是你所期望的：

clockType yourClock();

这是一个带零参数的函数的前向声明，并返回clockType的对象。你的真正含义是：

clockType yourClock;

// or
clockType yourClock = clockType();

这被称为"Most Vexing Parse"问题。

Answer 2

在您的代码中，

  clockType ();
  clockType (int hours = 0, int minutes = 0, int seconds = 0);

以上两个都可以在没有任何参数的情况下调用，因此两者都是默认构造函数。

由于您使用的是默认构造，编译器无法知道上述哪一个。

这是不明确的。

一种解决方案是删除参数默认值。

顺便说一句，你的operator++有一点问题;彻底测试，找到问题！ ; - ）

Answer 3

clockType ();
clockType (int hours = 0, int minutes = 0, int seconds = 0);

这些都可以用0参数构造。

有可能，你应该摆脱clockType();因为我假设这两个构造函数在没有参数的情况下调用时会做同样的事情。

Answer 4

此错误似乎与操作员声明无关。定义的构造函数为您创建了一个模糊的情况。

clockType ();
clockType (int hours = 0, int minutes = 0, int seconds = 0);

调用clockType（）时的意图是什么？根据上面的定义，有两个符合您要求的签名。没有构造函数参数，无参数版本和具有所有默认值的版本在逻辑上都可以工作。您需要确定他们的个人意图，然后编辑他们的定义以匹配。

C ++模糊运算符重载错误

4 个答案: