cannot find default constructor to initialize member in cpp

问题

Please help me with this. I was trying to fix this for two hours. This is my code.

class deviceC {

private:
    deviceA devA;
    deviceB devB;
    wayPoint destination,current;

public: 
    deviceC(wayPoint destination1){
        destination=destination1;
        devA=deviceA();
        devB=deviceB();
    }
};

This is the error:

cannot find default constructor to initialize member 'deviceC::destination' in function deviseC::destination(wayPoint)

回答1:

You need an initializer list in your constructor, because member destination and current with type wayPoint does not has a default constructor.

class deviceC {
public: 
    deviceC(wayPoint destination1) : destination(destination1) {
        devA=deviceA();
        devB=deviceB();
    }
};

And IMO, you don't need init the devA and devB inside the constructor just with the default constructor, they just call the operator= after their default constructor called. Here's my suggestion:

class deviceC {
private:
    deviceA devA;
    deviceB devB;
    wayPoint destination, current;
public: 
    deviceC(const wayPoint& destination1, const wayPoint& current1) : destination(destination1), current(current1) {}
};

回答2:

Missed a bracket.

class deviceC{

    private : deviceA devA;
                  deviceB devB;
                  wayPoint destination,current;

    public: deviceC(wayPoint destination1){
            destination=destination1;
            devA=deviceA();
            devB=deviceB();
    } // <-- here
};

来源：https://stackoverflow.com/questions/22852436/cannot-find-default-constructor-to-initialize-member-in-cpp