Question

A pointer that contains the address 0 is called a(n) __________ pointer.

Short answer

Answer: NULL pointer

Step-by-step solution

Definition of Pointer

A pointer is a variable that stores the memory address of another variable. Pointers are used in programming to efficiently manipulate data and memory.

Pointer with address 0

When a pointer has the address 0, it means that the pointer is not pointing to any valid memory location or object. In programming languages like C or C++, this special type of pointer is known as a NULL pointer. So, the correct answer is: A pointer that contains the address 0 is called a NULL pointer.

Key concepts

C++ Programming

C++ is a powerful general-purpose programming language that allows procedural, object-oriented, and generic programming paradigms. It's well-known for its powerful use of pointers—variables that hold the address of other variables. Understanding pointers is crucial for managing memory, developing complex data structures, and interfacing with low-level system components.

In C++, pointers add flexibility but they also add complexity. Proper use of pointers leads to more efficient programs; misuse, however, can lead to bugs and memory leaks. Thus, the difference between a NULL pointer and a non-NULL pointer is more than semantic detail—it's fundamental to writing robust and safe C++ programs.

Pointer Initialization

Pointer initialization in C++ refers to the process of assigning a pointer variable its initial value at the time of declaration. This can either be the address of an existing variable, dynamically allocated memory, or, as a safety measure, the NULL value indicating the pointer does not currently reference any memory location.

For instance, int *ptr = nullptr; here, 'ptr' is explicitly initialized to nullptr, which is a type-safe pointer literal introduced in C++11, replacing the need to use 0 or NULL. Initializing pointers to nullptr can help prevent undefined behavior such as accessing random memory, which can have unpredictable results and make debugging tedious.

Memory Management

In C++ programming, memory management is essential for the optimization of the application's performance and reliability. It involves the allocation, use, and deallocation of memory within a program's lifecycle. Correct management helps prevent memory leaks and crashes due to invalid memory access.

Dynamic memory management is done through the use of pointers with functions like new and delete. A NULL pointer serves as a sentinel value indicating that a pointer should not currently be used to access or deallocate memory, an important concept in preventing errors. It's common practice to set pointers to NULL after freeing the memory they point to, ensuring they do not accidentally get used later in the program.