No default constructor exists for class error

Question

Some simple code:

class Thing {
public:
    int num;
    Thing(int num) { 
        this->num = num; 
    }
};

class Stuff {
public:
    Thing thing;  //          


        

Answer 1

Initialize thing member in Stuff with initializer list:

class Stuff {
public:
    Thing thing;  // an instance of thing is declared here but it cannot construct it
    Stuff(Thing thing): thing(thing) { }
};