How to make Nested class, which use default constructor parameters?

[osfreak]

 
class Outer
{
public:
    int outera;
 
    class Inner{
 
    public:
        static int a,b;
        int c;
        void Displaystatvalue();
        Inner(int parm = 0):c(parm)
        {
        }
 
    }in1;         //}in1(15);//Not allowed why
        Inner in2;   //Inner in2(10);//not allowed,why?
 
};
 
 
 
 

[weaknessforcats]

in1 and in2 are member variables. in(15) and in2(10) are constructor calls. That is, actual code that executes and allocates memory. in(15)and in2(10) are , therefore definitions (objects created at run time), and you cannot have definitions inside a declaration because there's no way to make those calls at compile time.

[Banfa]

If you want to initialise the members of a class then you do it in the class initialisation list.

The initialisation list is something that can only be attached to a constructor and it specifies how to initialise class members as well as base classes.

In your case something like

Outer::Outer() :
  in2(10)
{
}
 

in much the same way you initialise the C member of Inner