What is a dangling pointer?

A dangling pointer occurs when a pointer points to a memory location that has been deallocated or released back to the system. This situation can arise after dynamic memory allocation when the memory is freed, but the pointer still holds the address of the now-invalid memory location. Accessing memory via a dangling pointer can lead to undefined behavior, crashes, or other unpredictable issues, as the memory could be reallocated for other purposes or corrupted.

The other options describe different issues with pointers, but they do not capture the essence of what constitutes a dangling pointer. An uninitialized pointer merely lacks a known address, which does not guarantee it points toward an invalid memory location. An incorrectly typecast pointer refers to mismatched data types, which might lead to improper handling of information but does not inherently involve memory deallocation. Lastly, a pointer that references a non-existent variable implies a direct reference issue rather than one involving deallocated memory. Thus, the focus on a memory location that has been deallocated correctly identifies the nature of a dangling pointer.