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 {
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
#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()
{ } |
References:
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2005/n1905.pdf
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