In C or C++ What is a dangling pointer?

Answer 1

A dangling pointer points to memory that has already been freed. The storage has been freed or variable been assigned the memory has it's life time ended, in other words storage no longer allocated. Now a pointer which is still holding the address of the same memory location which has been freed tries to access it causes segmentation fault to happen.

For example:-

int *x=(int *) malloc(4);
free(x);
*x=10; //THIS will cause the segmentation fault

Answer 2

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.