C++操作符超載會吐出垃圾值

Question

當前輸出是垃圾8位數值。我不太知道爲什麼除了功能不加入1和2 另外，我想如何實現一個功能：

TrashCan other = combined – myCan; 
cout << "the other cup's filled to " << other.getUsed() << endl; 

下面的代碼：

主：

int main() 

{ 
cout << "Welcome to Howie's TrashCan Program!" << endl; 

TrashCan myCan; 
TrashCan yourCan; 

yourCan.setSize(12); 
myCan.setSize(12); 

yourCan.addItem(); 
yourCan.addItem(); 
myCan.addItem(); 

myCan.printCan(); 
yourCan.printCan(); 

TrashCan combined = yourCan + myCan; 
cout << "this drive's filled to " << combined.getUsed() << endl;... 

類別：

class TrashCan { 
public: 
TrashCan(); 
TrashCan(int size); 
TrashCan(int size, int contents); 
TrashCan operator+(TrashCan); 
TrashCan operator-(TrashCan); 
void setSize(int size); 
void addItem(); 
void empty(); 
void cover(); 
void uncover(); 

void printCan(); 
int getUsed(); 

private: 
bool myIsCovered; 
int my_Size; 
int my_Contents; 
}; 

執行:(我假設我搞砸了一個o F中的以下功能）

TrashCan TrashCan::operator+ (TrashCan A) 
{ 
TrashCan combined; 
combined.my_Contents= my_Contents + A.my_Contents; 
} 

int TrashCan::getUsed() 
{ 
return my_Contents; 
} 

Answer 1

你不回臨時在你的函數：

TrashCan TrashCan::operator+ (TrashCan A) 
{ 
TrashCan combined; 
combined.my_Contents= my_Contents + A.my_Contents; 
// should be 
return combined; 
} 

Answer 2

試圖改變這種

TrashCan TrashCan::operator+ (TrashCan A) 
{ 
    TrashCan combined; 
    combined.my_Contents= my_Contents + A.my_Contents; 
} 

有了這個

TrashCan TrashCan::operator+ (TrashCan A) 
{ 
    this->my_Contents += A.my_Contents; 
    return *this; 
}