What is a dangling pointer?

What is a dangling pointer? 
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.