new and delete
new allocates on the heap and calls the constructor. delete calls the destructor and frees the memory. They must be paired — every new needs exactly one matching delete.
Node* n = new Node();
delete n;
int* arr = new int[10];
delete[] arr; // array new needs array delete - mixing these is undefined behaviorWhy nobody should write this directly
Forget the delete → leak. delete twice → crash or corrupted heap (see Rule of Five and deep copy). delete and keep using the pointer → dangling pointer, reading/writing memory you no longer own. This entire category of bug is why Smart pointers exist — they call delete for you, automatically, exactly once.