Skip to main content

Nested Classes in C++

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

#include<iostream>

using namespace std;

 /* start of Enclosing class declaration */
class Enclosing {    
     
   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

#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()
{
   
}

Posted By:-Cplusplusprogramming

Popular posts from this blog

C++ Program to find the sum, difference, product and quotient of two integers

#include <iostream.h> #include <conio.h> void main() {   clrscr();   int x = 10;   int y = 2;   int sum, difference, product, quotient;   sum = x + y;   difference = x - y;   product = x * y;   quotient = x / y;   cout << "The sum of " << x << " & " << y << " is " << sum << "." << endl;   cout << "The difference of " << x << " & " << "y <<  is " << difference << "." << endl;   cout << "The product of " << x << " & " << y << " is " << product << "." << endl;   cout << "The quotient of " << x << " & " << y << " is " << quotient << "." << endl;   getch(); }
Read more

Putimage function in c

putimage function outputs a bit image onto the screen. Declaration:- void putimage(int left, int top, void *ptr, int op); putimage puts the bit image previously saved with getimage back onto the screen, with the upper left corner of the image placed at (left, top). ptr points to the area in memory where the source image is stored. The op argument specifies a operator that controls how the color for each destination pixel on screen is computed, based on pixel already on screen and the corresponding source pixel in memory. c smiling face animation This animation using c draws a smiling face which appears at random position on screen. See output below the code, it will help you in understanding the code easily. C programming code #include<graphics.h> #include<conio.h> #include<stdlib.h>   main() { int gd = DETECT, gm, area, temp1, temp2, left = 25, top = 75; void *p;   initgraph(&gd,&gm,"C:\\TC\\BGI");   setcolor(YELLOW)...
Read more

What is Dynamic Memory Allocation in C++ Program

In the computer world, anything that is processed be it an instruction or any data first needs to be loaded and located in internal memory.  In C++ programs also any data that is processed while executing the program is held in the internal memory.  What is Dynamic Memory Allocation? Dynamic Memory allocation means that the memory that will be used during the program is not known beforehand and is allocated dynamically and on the go. It is allocated during the runtime as and when required by the program. In C++ there are two operators used in dynamic memory allocation  1. New  2. Delete New operator in dynamic memory allocation The new operator in C++ is used to create objects of all types. The new operator will allocate memory of the size of the data type specified in the program.  For Example iptr = new int ;  Storing initial values will allocate needed amount of memory from the free store to hold the value of the specified data-type and store the startin...
Read more