new operator in C++ - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the new operator do in C++?

The new operator allocates memory on the heap for a variable or object and returns a pointer to that memory.

beginner

How do you use new to create an integer on the heap?

You write int* p = new int; which allocates memory for an integer and stores its address in pointer p.

beginner

What must you do after using new to avoid memory leaks?

You must use delete to free the memory allocated by new when it is no longer needed.

intermediate

How do you allocate an array of 5 integers using new?

Use int* arr = new int[5]; to allocate an array of 5 integers on the heap.

intermediate

What is the difference between delete and delete[]?

delete frees memory allocated for a single object, while delete[] frees memory allocated for an array.

What does new return when it successfully allocates memory?

A A pointer to the allocated memory

B The value stored in the memory

C An integer representing the size

D Nothing, it just allocates silently

new returns a pointer to the memory it allocates on the heap.

Which operator should you use to free memory allocated with new[]?

A <code>delete</code>

B <code>free</code>

C <code>delete[]</code>

D <code>release</code>

Memory allocated with new[] must be freed with delete[] to avoid undefined behavior.

What happens if you forget to use delete after new?

A The program crashes immediately

B The memory is freed automatically

C The pointer becomes null

D Memory leak occurs

Forgetting delete causes memory leaks because allocated memory is not freed.

How do you allocate a single object of a class Car using new?

A Car* c = new Car();

B Car* c = Car();

C Car c = Car();

D Car c = new Car();

You allocate with new and store the pointer: Car* c = new Car();.

Which of the following is true about new?

A It allocates memory on the stack

B It allocates memory on the heap

C It automatically deletes memory

D It returns a reference

new allocates memory on the heap, not the stack.

Explain how the new operator works and why it is important to use delete afterwards.

Think about where memory is allocated and what happens if you don't free it.

Describe the difference between using new for a single object and for an array, including how to free each.

Focus on syntax and matching delete operators.