c++ - 在 C++ 结构中重载运算符 << 和 >>

Question

我有一个类和类中的结构:

class MyClass : public QObject
{
public:
    ....

    struct MyStruct
    {
       quint8 val1;
    }
};

我想为结构重载运算符 << 和 >>，但我不知道该怎么做。目前，我确实喜欢这样:

class MyClass : public QObject
{
public:
    ....

    struct MyStruct
    {
       quint8 val1;

       QDataStream &operator<<(QDataStream &out, const MyStruct& _myStruct)
       {
           out << _myStruct.val1;
           return out;
       }

       QDataStream &operator>>(QDataStream &in, MyStruct& _myStruct)
       {
           in >> _myStruct.val1;
           return in;
       }
    };
};

但是不行

Answer 1

您需要将运算符声明为friend:

       friend QDataStream &operator<<(QDataStream &out, const MyStruct& _myStruct)
       {
           out << _myStruct.val1;
           return out;
       }

       friend  QDataStream &operator>>(QDataStream &in, MyStruct& _myStruct)
       {
           in >> _myStruct.val1;
           return in;
       }