Pointers

Pointers are a unique feature in C++ that allow you to store memory addresses rather than values. They are useful for directly accessing and manipulating memory, enabling efficient data handling and dynamic memory allocation. In this section, we'll cover the basics of pointers, pointer arithmetic, and using pointers with arrays and functions.

Pointer Basics

A pointer is a variable that stores the memory address of another variable. Pointers can be of any type, such as int*, float*, or char*, depending on the data type they point to.

Syntax:

Example: Declaring and using a pointer.

In this example:

• number is a variable with an integer value.
• ptr is a pointer that stores the address of number.
• *ptr dereferences the pointer, giving us the value at that address.

Pointer Arithmetic

Pointer arithmetic involves adding or subtracting integer values from a pointer. Pointer arithmetic is particularly useful with arrays, as the pointer to the first element can traverse the entire array by adding or subtracting from it.

Example: Pointer arithmetic with an integer array.

In this example, ptr points to the first element of the array. Using *(ptr + i), we access each element by offsetting ptr by i positions.

Pointer to Arrays

Pointers can also be used to manipulate arrays. When we declare an array, the name of the array is a constant pointer to its first element.

Example: Pointer to an array.

In this example, arr is a pointer to the first element. We access the elements of the array by using pointer arithmetic.

Pointers to Functions

Pointers can also point to functions, allowing us to pass functions as arguments, store them in data structures, or assign them dynamically.

Syntax:

Example: Pointer to a function.

In this example:

• funcPtr is a pointer to the greet function.
• We use funcPtr() to call the function through the pointer.

Using Pointers with Arrays in Functions

Pointers are also useful in functions when we want to pass arrays as arguments, as arrays are passed by reference (using their address) rather than by value.

Example: Function that takes a pointer to an array.

Here:

• printArray takes a pointer to int (int* arr) and an integer size.
• We pass numbers to printArray, which iterates and prints each element using the pointer.