Nested Classes in C++

Last Updated : 23 Jul, 2025

A nested class is a class which is declared in another enclosing class. A nested class is a member and as such has the same access rights as any other member. The members of an enclosing class have no special access to members of a nested class; the usual access rules shall be obeyed. For example, program 1 compiles without any error and program 2 fails in compilation. Program 1

CPP

#include<iostream> using namespace std;  /* start of Enclosing class declaration */  class Enclosing {   private:   int x;    /* start of Nested class declaration */   class Nested {  int y;   void NestedFun(Enclosing *e) {  cout<<e->x; // works fine: nested class can access   // private members of Enclosing class  }   }; // declaration Nested class ends here }; // declaration Enclosing class ends here int main() {  }

Program 2

CPP

#include<iostream> using namespace std;  /* start of Enclosing class declaration */  class Enclosing {     int x;    /* start of Nested class declaration */   class Nested {  int y;   }; // declaration Nested class ends here  void EnclosingFun(Nested *n) {  cout<<n->y; // Compiler Error: y is private in Nested  }  }; // declaration Enclosing class ends here int main() {    }