What is Dangling pointer?

Dangling Pointer is a pointer that doesn’t point to a valid memory location. Dangling pointers arise when an object is deleted or deallocated, without modifying the value of the pointer, so that the pointer still points to the memory location of the deallocated memory. Following are examples.

// EXAMPLE 1
int *ptr = (int *)malloc(sizeof(int));
.............
.............
free(ptr); 
 
// ptr is a dangling pointer now and operations like following are invalid
*ptr = 10;  // or printf("%d", *ptr);
Run on IDE

// EXAMPLE 2
int *ptr = NULL
{
   int x  = 10;
   ptr = &x;
}
// x goes out of scope and memory allocated to x is free now.
// So ptr is a dangling pointer now.