C++ Tutorial/Class/protected
Версия от 14:21, 25 мая 2010; (обсуждение)
Demonstrate protected members.
#include <iostream>
using namespace std;
class BaseClass {
protected:
int i, j; // private to BaseClass, but accessible to DerivedClass
public:
void set(int a, int b) { i = a; j = b; }
void show() { cout << i << " " << j << "\n"; }
};
class DerivedClass : public BaseClass {
int k;
public:
// DerivedClass may access BaseClass"s i and j
void setk() {
k = i*j;
}
void showDerivedClass() {
cout << k << "\n";
}
};
int main()
{
DerivedClass ob;
ob.set(2, 3); // OK, set() is public in BaseClass
ob.show(); // OK, show is public BaseClass
ob.setk();
ob.showDerivedClass();
return 0;
}2 3 6
Protected Base-Class Inheritance
#include <iostream>
using namespace std;
class base {
protected:
int i, j; // private to base, but accessible by derived
public:
void setij(int a, int b) { i=a; j=b; }
void showij() { cout << i << " " << j << "\n"; }
};
// Inherit base as protected.
class derived : protected base{
int k;
public:
// derived may access base"s i and j and setij().
void setk() { setij(10, 12); k = i*j; }
// may access showij() here
void showall() { cout << k << " "; showij(); }
};
int main()
{
derived ob;
ob.setk(); // OK, public member of derived
ob.showall(); // OK, public member of derived
return 0;
}protected fields: private to base, but accessible by derived
#include <iostream>
using namespace std;
class base {
protected:
int i, j; //protected fields: private to base, but accessible by derived
public:
void set(int a, int b) {
i=a;
j=b;
}
void show() {
cout << i << " " << j << "\n";
}
};
class derived : public base {
int k;
public:
void setk() {
k=i*j;
}
void showk() {
cout << k << "\n";
}
};
int main()
{
derived ob;
ob.set(2, 3);
ob.show();
ob.setk();
ob.showk();
return 0;
}2 3 6
