In this specific case, is there a difference between using a member initializer list and assigning values in a constructor?

Question

Internally and about the generated code, is there a really difference between :

MyClass::MyClass(): _capacity(15), _data(NULL), _len(0)
{
}

Answer 1

Depends on the types involved. The difference is similar between

std::string a;
a = "hai";

and

std::string a("hai");

where the second form is initialization list- that is, it makes a difference if the type requires constructor arguments or is more efficient with constructor arguments.