範圍錯誤，不能有一個cv限定符？

Question

我與時間項目有關的問題，我將在下面完整發布以提供上下文。我所做的大部分都是正確的，但是在加法和減法操作符定義時，我遇到了範圍錯誤。編譯器找不到我的私有成員。 （如果用戶在25小時內進入小時，那麼操作員可以使用它，它會循環回到1）。項目作爲一個整體創建已定義方法的實例。無論如何，第二個錯誤與運營商本身有關。我得到一個錯誤

做研究告訴我，這個錯誤發生在改變const，在我的情況是時間本身。我看不到我在那裏做了什麼。我希望我很清楚，如果需要可以澄清。 .h文件來自練習本身，除了添加私人成員之外，我無法改變它。

#ifndef TIME_H_ 
#define TIME_H_ 

#include <iostream> 
#include <string> 
/*** Time class** The Time class contains time as 
hours:minutes:seconds:milliseconds (AM/PM).*/ 

class Time { 
public: 
/** * Constructor with zero values */ 
Time(); 

/** * Constructors with arguments */ 
Time(long long time); 
Time(int hours, int minutes, int seconds, int milli); 

/** * Deconstructor */ 
virtual ~Time(); 

/** * Return time as a long long value representing time in milliseconds */ 
long long asLong() const; 

/** * Provide a string in the format hours:minutes:seconds:milliseconds. * For example 1:45:30:56 PM */ 
std::string toString() const; 

/** * Output the time to an output stream as hours:minutes:seconds:milliseconds AM/PM */ 
friend std::ostream& operator <<(std::ostream&, const Time&); 

// Output a Time to an output stream 

/** * Declare ordering relationships */ 
friend bool operator <(const Time&, const Time&); 
friend bool operator >(const Time&, const Time&); 
friend bool operator ==(const Time &a, const Time &b); 

/** * Declare addition and subtraction */ 
Time operator +(const Time&) const; 
Time operator -(const Time&) const; 

private: 
int hours; 
int minutes; 
int seconds; 
int millis; 
}; 

#endif /* TIME_H_ */ 

然後，源自身。

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

using namespace std; 

// Defualt Constructor 
Time::Time() { 
    hours = 0; 
    minutes = 0; 
    seconds = 0; 
    millis = 0; 
} 

// Constructors with arguments 

Time::Time(long long timeValue) { 
    long long tempValue = timeValue; 
    millis = tempValue % 1000; 
    tempValue /= 1000; 
    seconds = tempValue % 60; 
    tempValue /= 60; 
    minutes = tempValue % 60; 
    tempValue /= 60; 
    hours = tempValue; 
} 

Time::Time(int hours, int minutes, int seconds, int millis) { 
    this->hours = hours; 
    this ->minutes = minutes; 
    this -> seconds = seconds; 
    this -> millis = millis; 

} 

// Destructor 
Time::~Time() { 

} 

// Return time in term of milliseconds. 

long long Time::asLong() const { 
    long long timeValue = (long long) hours; 
    timeValue = (timeValue * 60) + minutes; 
    timeValue = (timeValue * 60) + seconds; 
    timeValue = (timeValue * 1000) + millis; 
    return timeValue; 
} 

// Formatting 

std::string Time::toString() const { 
    ostringstream v1; 
    string ph; 

    if (hours <= 12) 
     ph = "am"; 
    else 
     ph = "pm"; 

    v1 << hours % 12 << ":" << minutes << ":" << seconds << ":" << millis << ph; 

    return v1.str(); 
} 

// Time to Output Stream 
ostream& operator <<(ostream& a, const Time& b) 
{ 
    return a << b.toString(); 
} 

// Ordering Relationships 
bool operator <(const Time&t1, const Time&t2) 
{ 
    return t1.asLong() < t2.asLong(); 
} 

bool operator >(const Time&t1, const Time&t2) 
    { 
    return t1.asLong() > t2.asLong(); 
} 
bool operator ==(const Time &a, const Time &b) 
{ 
    return a.asLong() == b.asLong(); 
} 

// Declare addition and Subtraction 
Time operator +(const Time&) const 
{ 
    int a,b,c,d; 
    a = t1.hours+t2.hours; 
    b = t1.minutes+t2.minutes; 
    c = t1.seconds+t2.seconds; 
    d = t1.millis+t2.millis; 
    if (d > 999) 
    { 
     c = c+1; 
     d = d - 1000; 
    } 
    if (c > 59) 
    { 
     b = b + 1; 
     c = c - 60; 
    } 
    if (b > 59) 
    { 
     a = a+1; 
     b = b-60; 
    } 
    if (a > 24) 
    { 
     a = a - 24; 
    } 
    return Time(a,b,c,d); 
} 
    Time operator -(const Time&) const 
    { 
     int a,b,c,d; 
     a = t1.hours-t2.hours; 
     b = t1.minutes-t2.minutes; 
     c = t1.seconds-t2.seconds; 
     d = t1.millis - t2.millis; 
     if (d < 0) 
     { 
      c = c -1; 
      d = d + 1000; 
     } 
     if (c < 0) 
     { 
      b = b - 1; 
      c = c + 60; 
     } 
     if (b < 0) 
     { 
      a = a + 1; 
      b = b - 60; 
     } 
     if (a < 24) 
     { 
     a = a + 24; 
     } 

     return Time(a,b,c,d); 
    } 

Answer 1

如果非成員函數是friend函數。在非成員函數中，沒有參數this。他們不需要cv-qualifier。你爲什麼不改變：

friend bool operator <(const Time&, const Time&); 
friend bool operator >(const Time&, const Time&); 
friend bool operator ==(const Time &a, const Time &b); 

到

bool operator <(const Time &a); 
bool operator >(const Time &a); 
bool operator ==(const Time &a);