Question 1

Each time a new shared_ptr to the resource is created, the reference count ________, and each time one is destroyed, the reference count ________.
A) increases, increases
B) increases, decreases
C) decreases, increases
D) decreases, decreases

Accepted Answer

When a new shared_ptr to the resource is created, the reference count increases because there is a new owner of the resource. Conversely, when a shared_ptr is destroyed, the reference count decreases because one owner of the resource no longer exists. Therefore, the answer is B: each time a new shared_ptr is created, the reference count increases, and each time one is destroyed, the reference count decreases.

Question 2

A copy constructor, a destructor and an overloaded assignment operator are usually provided as a group for any class that uses dynamically allocated memory. With the addition of move semantics in C++11, you should also provide __________.
A) a move constructor
B) a move assignment operator
C) an overloaded move destructor
D) both a and b

Accepted Answer

Move semantics is used to efficiently move resources rather than copying them. With dynamic memory allocation used in a class, it is recommended to provide both move constructor and move assignment operator to ensure efficient and safe transfer of resources. Therefore, both option A and B are correct. Option C is incorrect as there is no concept of an overloaded move destructor in C++.

Question 3

A unique_ptr automatically calls ________ to free its associated dynamic memory when the unique_ptr is destroyed or goes out of scope.
A) release
B) destroy
C) erase
D) delete

Accepted Answer

A unique_ptr automatically calls delete to free its associated dynamic memory when the unique_ptr is destroyed or goes out of scope, making D the correct choice. Release is a method that disassociates the unique_ptr from the managed object without freeing the memory, destroy and erase are not valid methods for a unique_ptr.

Question 4

The ________ multithreading header contains class thread for manually creating and starting threads, and functions yield, get_id, sleep_for and sleep_until. A) B) C) D)

Accepted Answer

The <thread> header in C++ contains the class thread for manually creating and starting threads, as well as various functions including yield, get_id, sleep_for, and sleep_until. The other headers listed do not include these specific functionalities.

Question 5

Weak_ptrs should be used in any situation where you need to ________ the resource but don't want to assume any management responsibilities for it.
A) delete
B) copy
C) observe
D) move

Accepted Answer

Weak_ptrs are primarily used for observing resources rather than managing them. They provide a non-owning reference to an object, which means that they can be used to access the object but cannot modify or manage it. Therefore, option C, "observe," is the best choice for the situation described in the question.

Question 6

Which statement is false:
A) A weak_ptr points to the resource managed by a shared_ptr without assuming any responsibility for it.
B) The reference count for a shared_ptr doesn't increase when a weak_ptr references it. That means that the resource of a shared_ptr can be deleted while there are still weak_ptrs pointing to it. When the last shared_ptr is destroyed, the resource is deleted and any remaining weak_ptrs are set to NULL.
C) One use for weak_ptr s is to avoid memory leaks caused by circular references.
D) None of the above.

Accepted Answer

All of the statements are true.

Question 7

The internal pointer is deleted once the last ________ to the resource is destroyed.
A) smart pointer
B) shared_ptr
C) weak_ptr
D) link

Accepted Answer

The internal pointer is deleted once the last `shared_ptr` to the resource is destroyed. `shared_ptr` manages the memory of a shared resource and deletes the internal pointer when the last `shared_ptr` pointing to the resource is destroyed.

Question 8

The ________ multithreading header contains classes and class templates for ensuring mutually exlusive access to resources shared among threads in an application. A) B) C) D)

Accepted Answer

The <mutex> header contains classes and class templates for ensuring mutually exclusive access to resources shared among threads in an application. A mutex is a synchronization primitive that can be used to protect shared data from being simultaneously accessed and modified by multiple threads.

Question 9

When the reference count reaches zero, the ________ is deleted and the memory is released.
A) internal pointer
B) external pointer
C) internal reference
D) external reference

Accepted Answer

When the reference count of an internal pointer reaches zero, it indicates that there are no more references to the object it points to, leading to the deletion of the object and the release of the memory it occupied. This is a key mechanism in garbage collection and memory management in programming languages that use reference counting.

Question 10

In the following function int square(int value)
{
Return value * value;
}
The noexcept keyword indicates that this function ________.
A) does not catch exceptions
B) does not throw exceptions
C) does not test for exceptions
D) None of the above.

Accepted Answer

The noexcept keyword indicates that the function does not throw any exceptions.

Question 11

Which of the following statements is false?
A) The thread launch policy is a value from the launch enum-either launch::async, launch::deferred or both separated by a bitwise OR (|) operator.
B) The thread launch policy value launch::async indicates that a specified function should execute in the current thread.
C) Function async returns an object of class template future that you can use when the thread completes execution to obtain data returned by the function that async executes. The thread launch policy value launch::deferred indicates that a specified function should execute in the same thread when the program uses the future object returned by function template async to get the result.
D) To ensure that a program does not terminate until its threads terminate and to receive the results from each thread, we call each future's get member function. This causes the program to wait until the corresponding threads complete execution-known as joining the threads-before executing the remaining code in main.

Accepted Answer

The statement "The thread launch policy value launch::async indicates that a specified function should execute in the current thread" is false. launch::async indicates that the function should execute in a new thread.

Question 12

There are many cases in which the object being copied is about to be destroyed, such as a temporary object that was returned from a function by value or a local object that's going out of scope. In such cases, it's better to move the contents of the object that's about to be destroyed into the destination object, thus avoiding ________.
A) a memory leak
B) a runtime error
C) a memory exhaustion error
D) any copying overhead

Accepted Answer

Moving the contents of the object that's about to be destroyed avoids any copying overhead, improving performance. It also prevents memory leaks, runtime errors, and memory exhaustion errors.

Question 13

The ________ multithreading header contains class templates, a function template and enums that enable you specify functions to execute in separate threads and to receive the results of those functions when the threads complete. A) B) C) D)

Accepted Answer

The <future> header contains class templates such as std::future, std::shared_future, and std::promise, which allow you to execute functions asynchronously in separate threads and retrieve the result of the function when the thread completes.

Question 14

Which statements is false:
A) shared_ptrs provide the pointer operators dot(.), star(*) and arrow(->).
B) We get the reference count using the shared_ptr member function use_count, which returns the number of shared_ptrs to the resource.
C) Changes made to the resource of a shared_ptr are "seen" by all shared_ptrs to that resource.
D) shared_ptr member function reset releases the current resource and sets the shared_ptr to NULL. If there are no other shared_ptrs to the resource, it's destroyed.

Accepted Answer

shared_ptrs provide the arrow(->) operator for accessing members of the pointed object, but not the dot(.) operator.

Question 15

The ________ multithreading header contains classes, a function and an enum that are used together with facilities in header to implement thread synchronization. In particular, condition variables can be used to make threads wait for a specific condition in a program, then to notify the waiting threads when that condition is satisfied. A) B) C) D)

Accepted Answer

The header contains classes, a function and an enum that are used together with facilities in header to implement thread synchronization. In particular, condition variables can be used to make threads wait for a specific condition in a program, then to notify the waiting threads when that condition is satisfied.

Question 16

Which statement is false?
A) There's overhead inherent in multithreading.
B) Simply dividing a task into two threads and running it on a dual core system does not run it twice as fast, though it will typically run faster than performing the thread's tasks in sequence on one core.
C) Executing a multithreaded application on a single-core processor can actually take longer than simply performing the thread's tasks in sequence.
D) None of the above.

Accepted Answer

All the statements are true, hence option D is the false statement.

Question 17

Smart pointers ________.
A) strengthen the process of memory allocation and deallocation
B) help you write exception safe code
C) help prevent memory leaks
D) all of the above

Accepted Answer

Smart pointers are objects that behave like pointers but have additional functionality for memory management. They provide a safer and more reliable approach to memory allocation and deallocation. By using smart pointers, you can write exception safe code, as they automatically handle memory cleanup and prevent memory leaks. Therefore, all of the above are correct.

Question 18

If a program throws an exception before delete has been called on a pointer, it creates a memory leak. After an exception is thrown, a(n) ________ destructor will still be called, which calls delete on the pointer for you.
A) reference's
B) inherited
C) smart pointer's
D) virtual

Accepted Answer

Using a smart pointer, such as std::unique_ptr, automatically manages the memory for you and will call delete on the pointer even if an exception is thrown. This helps prevent memory leaks and ensures proper memory management.

Question 19

Shared_ptrs use ________ counting to determine how many shared_ptrs point to the resource.
A) pointer
B) link
C) smart pointer
D) reference

Accepted Answer

Shared_ptrs use reference counting to keep track of how many shared_ptrs are pointing to the same resource. When the count reaches zero, the resource is deallocated.

Question 20

Though multithreading has been around for decades, interest in it is rising quickly due to the proliferation of ________ systems.
A) virtual
B) object-oriented
C) polymorphic
D) multicore

Accepted Answer

Multithreading becomes advantageous in systems with multiple processors or cores, where multiple threads can be executed in parallel. Therefore, the proliferation of multicore systems has led to increased interest in multithreading. Virtual, object-oriented, and polymorphic are not directly related to the rise of interest in multithreading.

Quiz 24: C++11 Additional Features

Each time a new shared_ptr to the resource is created, the reference count , and each time one is destroyed, the reference count .

A copy constructor, a destructor and an overloaded assignment operator are usually provided as a group for any class that uses dynamically allocated memory. With the addition of move semantics in C++11, you should also provide __________.

A unique_ptr automatically calls ________ to free its associated dynamic memory when the unique_ptr is destroyed or goes out of scope.

The ________ multithreading header contains class thread for manually creating and starting threads, and functions yield, get_id, sleep_for and sleep_until.

Weak_ptrs should be used in any situation where you need to ________ the resource but don't want to assume any management responsibilities for it.

Which statement is false:

The internal pointer is deleted once the last ________ to the resource is destroyed.

The ________ multithreading header contains classes and class templates for ensuring mutually exlusive access to resources shared among threads in an application.

When the reference count reaches zero, the ________ is deleted and the memory is released.

In the following function int square(int value) { Return value * value; } The noexcept keyword indicates that this function ________.

Which of the following statements is false?

The ________ multithreading header contains class templates, a function template and enums that enable you specify functions to execute in separate threads and to receive the results of those functions when the threads complete.

Which statements is false:

Which statement is false?

Smart pointers ________.

If a program throws an exception before delete has been called on a pointer, it creates a memory leak. After an exception is thrown, a(n) ________ destructor will still be called, which calls delete on the pointer for you.

Shared_ptrs use ________ counting to determine how many shared_ptrs point to the resource.

Though multithreading has been around for decades, interest in it is rising quickly due to the proliferation of ________ systems.