C++ Pointers

In C++, a pointer is a variable that stores the memory address of another variable. Pointers allow you to manipulate and access memory directly, enabling advanced memory management and efficient handling of data structures. In this article, we will explore the usage of pointers in C++ with examples.

1. Declaring and Initializing Pointers

To declare a pointer in C++, you use the asterisk (*) before the pointer name. You can initialize a pointer by assigning the address of a variable to it using the address-of operator (&). Here's an example:

#include <iostream>

int main() {
    int number = 10;
    int* pointer = &number;

    std::cout << "Value of number: " << number << std::endl;
    std::cout << "Address of number: " << &number << std::endl;
    std::cout << "Value of pointer: " << pointer << std::endl;
    std::cout << "Value pointed to by pointer: " << *pointer << std::endl;

    return 0;
}

In the above code, we declare an integer variable number and a pointer variable pointer. We assign the address of number to pointer. The * operator is used to dereference the pointer and access the value it points to.

2. Pointer Arithmetic

Pointers in C++ support arithmetic operations such as addition and subtraction. Here's an example:

#include <iostream>

int main() {
    int numbers[] = {1, 2, 3, 4, 5};
    int* pointer = numbers;

    std::cout << "First element: " << *pointer << std::endl;
    std::cout << "Second element: " << *(pointer + 1) << std::endl;
    std::cout << "Third element: " << *(pointer + 2) << std::endl;

    return 0;
}

In the above code, we declare an integer array numbers and a pointer pointer pointing to the first element of the array. We use pointer arithmetic to access the elements of the array by incrementing the pointer.

3. Dynamic Memory Allocation

Pointers are commonly used in dynamic memory allocation to allocate memory during runtime. Here's an example:

#include <iostream>

int main() {
    int* pointer = new int;  // Allocate memory

    *pointer = 10;  // Assign value

    std::cout << "Value: " << *pointer << std::endl;

    delete pointer;  // Deallocate memory

    return 0;
}

In the above code, we use the new operator to allocate memory for an integer variable. We assign a value to the memory location using the dereferenced pointer. Finally, we deallocate the memory using the delete operator to prevent memory leaks.

4. Pointers and Functions

Pointers are often used to pass arguments by reference to functions, allowing the function to modify the original value. Here's an example:

#include <iostream>

void square(int* number) {
    *number = *number * *number;
}

int main() {
    int number = 5;

    square(&number);

    std::cout << "Squared value: " << number << std::endl;

    return 0;
}

In the above code, we define a function square that takes a pointer to an integer as a parameter. The function squares the value pointed to by the pointer. We pass the address of the number variable to the function using the address-of operator (&).

Pointers provide powerful capabilities in C++ for memory manipulation and advanced data handling. They enable dynamic memory allocation, pointer arithmetic, and passing arguments by reference. Mastering the use of pointers allows you to efficiently manage memory and build more sophisticated algorithms and data structures in your C++ programs.