Nested Classes in C++ (original) (raw)
Last Updated : 04 Jan, 2019
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
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<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
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<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