Has the new C++11 member initialization feature at declaration made initialization lists obsolete?

Question

With C++11, we now have the ability to initialize class members in a header declaration:

class aClass
{
    private:
        int mInt{100};
    public:
              


        

Answer 1

No, they are not obsolete.

Initialization lists are still the only way to go if you need a constructor's arguments to initialize your class members.

class A
{
  int a=7; //fine, give a default value
public:
  A();
};

class B
{
  int b; 
public:
  B(int arg) : b(arg) {}

  B(int arg, bool b) : b(arg) { ... }
};

Note that if both are present, the constructor's initialization will take effect, overriding the class member initialization, which is useful to specify a default value for a class member.