[help] const_cast

[Kaspar Minosiants]

Hi ,
there is a question about work of const_cast

The question is why the object is still reachable after a delete operation

class A {
int var;
public:
A():var(0){}
~A(){}
void setVar(int a){var=a;}
int getVar() const {return var;}
int getVar() {return var;}
};
int main() {

const A* a=new A();
A *b=const_cast<A*>(a);
delete a;
b->setVar(10);
cout<<b->getVar();
return 0;
}

 

[Peter van Merkerk]

there is a question about work of const_cast

The question is why the object is still reachable after a delete operation

class A {
int var;
public:
A():var(0){}
~A(){}
void setVar(int a){var=a;}
int getVar() const {return var;}
int getVar() {return var;}
};
int main() {

const A* a=new A();
A *b=const_cast<A*>(a);
delete a;
b->setVar(10);
cout<<b->getVar();
return 0;
}

Undefined behaviour, anything might happen. const_cast has nothing to do
with this.

 

[John Harrison]

Hi ,
there is a question about work of const_cast

The question is why the object is still reachable after a delete operation

class A {
int var;
public:
A():var(0){}
~A(){}
void setVar(int a){var=a;}
int getVar() const {return var;}
int getVar() {return var;}
};
int main() {

const A* a=new A();
A *b=const_cast<A*>(a);
delete a;
b->setVar(10);
cout<<b->getVar();
return 0;
}

Well what would you expect to happen? Its not a compile error, so what sort
of error?

The truth is that accessing an object after it has been deleted is an
example of 'undefined behaviour', which means ANYTHING could happen,
including your program 'working'.

This has nothing to do with const_cast.

john