0 — Test 584

Correct Answer: C. Memory leak
Explanation: Standard C++ has no garbage collector, so unreleased heap memory stays allocated until the process exits.

Correct Answer: A. Undefined behavior; delete[] p must be used
Explanation: new must be paired with delete, and new[] with delete[]. Mismatching them is undefined behavior. ALSO KNOW (related points): • In C++, where are local (automatic) variables and memory allocated with new typically stored? → Locals on the stack; new on the heap (free store) • What happens when memory allocated with new in C++ is never released with delete? → Memory leak • What happens when a null pointer is dereferenced in C++? → Undefined behavior (commonly a segmentation fault)

Correct Answer: D. It returns a dangling pointer to a local variable that no longer exists
Explanation: x is destroyed when f returns. Dereferencing the returned pointer is undefined behavior. ALSO KNOW (related points): • How does CPython primarily manage memory? → Reference counting, plus a cyclic garbage collector • Given int arr[5]; int *p = arr; with 4-byte ints, how many bytes does p + 2 advance from arr? → 8 bytes • What does C's malloc return when the requested memory cannot be allocated? → NULL

Correct Answer: A. Reference counting, plus a cyclic garbage collector
Explanation: Reference counting frees most objects immediately. The gc module handles reference cycles.

Correct Answer: C. 8 bytes
Explanation: Pointer arithmetic is scaled by the size of the pointed-to type: 2 × sizeof(int) = 8 bytes.

Correct Answer: D. Undefined behavior (commonly a segmentation fault)
Explanation: C++ throws no exception here. NullPointerException belongs to Java.

Correct Answer: B. NULL
Explanation: malloc returns NULL on failure. C++ new throws std::bad_alloc, unless the nothrow form is used.

Correct Answer: B. Base::show()
Explanation: Without virtual, the call is bound at compile time using the pointer's static type (Base). ALSO KNOW (related points): • Why can't the this pointer be used inside a static member function? → A static member function is not called on an object, so there is no this

Correct Answer: C. Destructors can be virtual; constructors cannot
Explanation: A base class used polymorphically should have a virtual destructor, so deleting through a base pointer calls the derived destructor.

Correct Answer: C. It has at least one pure virtual function (= 0)
Explanation: C++ has no abstract keyword (Java and C# do). An abstract class cannot be instantiated. ALSO KNOW (related points): • Which C++ members can be declared virtual? → Destructors can be virtual; constructors cannot • What is the default member access in a C++ class and in a C++ struct? → class: private; struct: public • Which statement correctly distinguishes overloading from overriding? → Overloading is resolved at compile time; overriding a virtual function is resolved at run time • In Python, a class defines self.__secret = 1. Which statement is true? → The name is mangled to _ClassName__secret but is still accessible from outside • Which statement about a C++ friend function is correct? → It is not a member of the class but can access the class's private members • A Car class holds an Engine object as a data member. Which relationship is this? → Composition (has-a)