CODEWITHSUNDEEP
c++
user7637341
user7637341

Reputation: 481

Can you call a constructor for a base class to create a derived object?

class class1 {
public:
    class1(int x);

};

class class2 : public class1 {
};

Can I do:

class2 my_class2(10);

Or do I have to define the constructor again for class2 (even though it does exactly the same thing)?

Upvotes: 3

Views: 58

Answers (2)

ltjax
ltjax

Reputation: 15997

Since C++17, you can directly call public base-class constructors via aggregate initialization - without adding any code to the classes:

class2 my_class2{2}; // Note the curly braces!

Upvotes: 3

jfMR
jfMR

Reputation: 24738

Since C++11 constructors can be inherited:

class class2 : public class1 {
public:
    using class1::class1;
};

Otherwise you have to do the following:

class class2 : public class1 {
public:
    class2(int x): class1(x) {}
};

A constructor of the base class has to be called anyway when constructing an object of the derived class.

Upvotes: 6

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