सी ++ में किसी ऑब्जेक्ट की जांच करने के लिए कोई सीधी विधि नहीं है, कुछ वर्ग प्रकार का उदाहरण है या नहीं। Java में हमें इस तरह की सुविधा मिल सकती है।
C++11 में, हम is_base_of
dynamic_cast
उदाहरण कोड
#include <iostream>
using namespace std;
template<typename Base, typename T>
inline bool instanceof(const T *ptr) {
return dynamic_cast<const Base*>(ptr) != nullptr;
}
class Parent {
public:
virtual ~Parent() {}
virtual void foo () { std::cout << "Parent\n"; }
};
class Child : public Parent {
public:
virtual void foo() { std::cout << "Child\n"; }
};
class AnotherClass{};
int main() {
Parent p;
Child c;
AnotherClass a;
Parent *ptr1 = &p;
Child *ptr2 = &c;
AnotherClass *ptr3 = &a;
if(instanceof<Parent>(ptr1)) {
cout << "p is an instance of the class Parent" << endl;
} else {
cout << "p is not an instance of the class Parent" << endl;
}
if(instanceof<Parent>(ptr2)) {
cout << "c is an instance of the class Parent" << endl;
} else {
cout << "c is not an instance of the class Parent" << endl;
}
if(instanceof<Child>(ptr2)) {
cout << "c is an instance of the class Child" << endl;
} else {
cout << "c is not an instance of the class Child" << endl;
}
if(instanceof<Child>(ptr1)) {
cout << "p is an instance of the class Child" << endl;
} else {
cout << "p is not an instance of the class Child" << endl;
}
if(instanceof<AnotherClass>(ptr2)) {
cout << "c is an instance of AnotherClass class" << endl;
} else {
cout << "c is not an instance of AnotherClass class" << endl;
}
} आउटपुट
p is an instance of the class Parent c is an instance of the class Parent c is an instance of the class Child p is not an instance of the class Child c is not an instance of AnotherClass class