Error : base class constructor must explicitly initialize parent class constructor

Question

I am new to c++. When I try to compile the code below , I get this error

constructor for \'child\' must explicitly initialize the base class \'parent\' whic

Answer 1

When you initialize an object of a derived class, the base class part has to be constructed first. If you don't initialize it yourself in the derived class' constructor by calling one of its constructors, the compiler will attempt use the default constructor of the base class. In your case the default constructor is not defined because you already provided a custom constructor.

To solve this you will either have to provide a default constructor for the base class or simply call its constructor in the derived class' constructor's initializer list:

child::child(int a) : parent(a)
 {
 }