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What is the difference between the stack and the heap? What do new and delete do? What is a memory leak? What is the difference between malloc/free and new/delete? What is placement new? What causes a stack overflow? What is RAII and how does it relate to memory management? What is the difference between shallow copy and deep copy in memory terms? What is memory alignment and why does it matter? What is the difference between a memory leak and a resource leak?
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C++ › Memory Management

What is a dangling pointer and how does it arise?

Intermediate

Answer

A dangling pointer points to memory that has been freed or gone out of scope, so dereferencing it is undefined behavior. It arises from using a pointer after delete, returning the address of a local variable, or holding a pointer/iterator into a container after it reallocates. Setting freed pointers to nullptr and using smart pointers reduces the risk.
int* p = new int(5);
delete p;
*p = 10;   // dangling: undefined behavior
Real-world example A cached raw pointer crashes the app after the object it referenced was destroyed.

Common follow-ups: How do you avoid dangling pointers? | What is use-after-free?

References & Pointers RAII & Smart Pointers Memory Management
All 12 Memory Management questions