#include <iostream> using namespace std; class Time; class Time { friend ostream& operator << (ostream &os, const Time &t); friend Time operator + (const Time & t1, const Time & t2); private: int hours; int minutes; public: Time(); Time(int h, int m = 0 ) { hours = h; minutes = m; } void AddMin(int m); void AddHr(int h); void Reset(int h=0, int m=0); Time Sum(const Time &t) const; // Time operator + (const Time &t) const; void Show() const; }; Time::Time() { hours = 0; minutes = 0; } void Time::AddMin(int m) { minutes += m; hours = minutes / 60; minutes %= 60; } void Time::AddHr(int h) { hours += h; } Time Time::Sum(const Time &t) const { Time sum; sum.minutes = minutes + t.minutes; sum.hours = hours + t.hours + sum.minutes / 60; sum.minutes %= 60; return sum; } Time operator + (const Time & t1, const Time & t2) { Time sum; sum.minutes = t1.minutes + t2.minutes; sum.hours = t1.hours + t2.hours + sum.minutes / 60; sum.minutes %= 60; return sum; } ostream& operator << (ostream &os, const Time &t) { os << t.hours << ":" << t.minutes; return os; } int main() { Time a; return 0; }
1 #include <iostream> 2 3 using namespace std; 4 5 class Time; 6 class Time 7 { 8 friend ostream& operator << (ostream &os, const Time &t); 9 friend Time operator + (const Time & t1, const Time & t2); 10 private: 11 int hours; 12 int minutes; 13 public: 14 Time(); 15 Time(int h, int m = 0 ); 16 void AddMin(int m); 17 void AddHr(int h); 18 void Reset(int h=0, int m=0); 19 Time Sum(const Time &t) const; 20 // Time operator + (const Time &t) const; 21 void Show() const; 22 23 }; 24 25 Time::Time() 26 { 27 hours = 0; 28 minutes = 0; 29 } 30 31 Time::Time(int h, int m = 0) 32 { 33 hours = h; 34 minutes = m; 35 } 36 37 void Time::AddMin(int m) 38 { 39 minutes += m; 40 hours = minutes / 60; 41 minutes %= 60; 42 } 43 44 void Time::AddHr(int h) 45 { 46 hours += h; 47 48 } 49 50 Time Time::Sum(const Time &t) const 51 { 52 Time sum; 53 sum.minutes = minutes + t.minutes; 54 sum.hours = hours + t.hours + sum.minutes / 60; 55 sum.minutes %= 60; 56 return sum; 57 58 59 } 60 61 62 Time operator + (const Time & t1, const Time & t2) 63 { 64 Time sum; 65 sum.minutes = t1.minutes + t2.minutes; 66 sum.hours = t1.hours + t2.hours + sum.minutes / 60; 67 sum.minutes %= 60; 68 return sum; 69 } 70 71 ostream& operator << (ostream &os, const Time &t) 72 { 73 os << t.hours << ":" << t.minutes; 74 return os; 75 } 76 77 78 int main() 79 { 80 Time a; 81 82 return 0; 83 }
出错 意思是声明或者定义只需要出现一次默认参数的值，将15行或者31行中的默认参数删除一个即可
miao@openlib:~/cpp_tset/cpp_develop$ g++ operator_test1.cpp -o operator_test1 operator_test1.cpp:31:28: error: default argument given for parameter 2 of ‘Time::Time(int, int)’ [-fpermissive] Time::Time(int h, int m = 0) ^ operator_test1.cpp:15:3: note: previous specification in ‘Time::Time(int, int)’ here Time(int h, int m = 0 );