C++ Programming Interview Question:

What is a dangling pointer in C++?

Submitted by: Administrator

A dangling pointer arises when you use
the address of an object after
its lifetime is over. This may occur
in situations like returning
addresses of the automatic variables
from a function or using the
address of the memory block after
it is freed. The following
code snippet shows this:

class Sample
{
public:
int *ptr;
Sample(int i)
{
ptr = new int(i);
}

~Sample()
{
delete ptr;
}
void PrintVal()
{
cout << "The value is " << *ptr;
}
};

void SomeFunc(Sample x)
{
cout << "Say i am in someFunc " << endl;
}

int main()
{
Sample s1 = 10;
SomeFunc(s1);
s1.PrintVal();
}

In the above example when PrintVal() function is
called it is called by the pointer that has been
freed by the destructor in SomeFunc.

Submitted by: Administrator