Some pointers on pointers

PublishedDecember 23, 2023

I am Jyotiprakash, a deeply driven computer systems engineer, software developer, teacher, and philosopher. With a decade of professional experience, I have contributed to various cutting-edge software products in network security, mobile apps, and healthcare software at renowned companies like Oracle, Yahoo, and Epic. My academic journey has taken me to prestigious institutions such as the University of Wisconsin-Madison and BITS Pilani in India, where I consistently ranked among the top of my class.

At my core, I am a computer enthusiast with a profound interest in understanding the intricacies of computer programming. My skills are not limited to application programming in Java; I have also delved deeply into computer hardware, learning about various architectures, low-level assembly programming, Linux kernel implementation, and writing device drivers. The contributions of Linus Torvalds, Ken Thompson, and Dennis Ritchie—who revolutionized the computer industry—inspire me. I believe that real contributions to computer science are made by mastering all levels of abstraction and understanding systems inside out.

In addition to my professional pursuits, I am passionate about teaching and sharing knowledge. I have spent two years as a teaching assistant at UW Madison, where I taught complex concepts in operating systems, computer graphics, and data structures to both graduate and undergraduate students. Currently, I am an assistant professor at KIIT, Bhubaneswar, where I continue to teach computer science to undergraduate and graduate students. I am also working on writing a few free books on systems programming, as I believe in freely sharing knowledge to empower others.

Comments

Join the discussion

No comments yet. Be the first to comment.

C Programming

Part 12 of 50

Up next

Even pointers have to do maths!

Understanding Pointer Arithmetic in C: A Hands-on Guide Pointer arithmetic is a powerful feature in the C programming language that allows for efficient navigation through memory. It's a concept that often confuses beginners but is fundamental for ta...

More from this blog

Why Energy and Momentum Are Conserved: Noether's Theorem, Derived by Hand

Two conservation laws, derived from scratch with first-year calculus, then measured to check.

Aug 10, 202630 min read

Socket Programming in Java: Understanding TCP Communication

Socket programming forms the backbone of network communication in modern applications. Whether you're building a web service, a chat application, or a distributed system, understanding how to work wit

Aug 6, 202626 min read

Computer Arithmetic: From Fast Adders to Floating-Point

Arithmetic is the beating heart of every processor. Whether your machine is rendering 3-D graphics, training a neural network, or simply incrementing a loop counter, the ALU (Arithmetic Logic Unit) is doing the heavy lifting. In this deep-dive, I wan...

Feb 12, 202629 min read

The Complete Memory Hierarchy: From Semiconductor RAM to Virtual Memory

The performance gap between processors and main memory has been widening for decades. Modern processors can execute billions of instructions per second, but accessing data from main memory takes hundreds of processor cycles. This disparity creates a ...

Jan 7, 202670 min read

The Ultimate Spring Boot Guide: From Fundamentals to Production-Ready REST APIs

Introduction Welcome to the most comprehensive Spring Boot guide you'll find! This isn't just another tutorial that skims the surface. We're going to dive deep into every concept, explain every annotation, walk through every line of code, and underst...

Dec 26, 2025125 min read

Jyotiprakash's Blog

253 posts

I'm Jyotiprakash, a software dev and professor at KIIT, with expertise in system programming.

In the C programming language, a pointer is a variable that stores the memory address of another variable. Pointers are powerful and versatile features of C that allow you to work with memory at a low level. Understanding pointers is crucial for tasks such as dynamic memory allocation, data structures, and efficient manipulation of memory.

Here are the key concepts related to pointers in C:

1. Declaration and Initialization:

int *ptr;   // Declaring a pointer to an integer
int num = 10;
ptr = &num;  // Initializing the pointer with the address of 'num'

2. & (Address-of) Operator:

The & operator is used to get the address of a variable.

int num = 10;
int *ptr = &num;  // ptr now holds the address of 'num'

3. * (Dereference) Operator:

The * operator is used to access the value stored at the address held by a pointer.

int num = 10;
int *ptr = &num;
printf("Value of num: %d\n", *ptr);  // Prints the value of 'num'

4. Pointer Arithmetic:

Pointers can be incremented or decremented to navigate through memory.

int arr[5] = {1, 2, 3, 4, 5};
int *ptr = arr;  // Points to the first element of the array

printf("Value at ptr: %d\n", *ptr);  // Prints the first element (1)
ptr++;  // Moves to the next element
printf("Value at ptr: %d\n", *ptr);  // Prints the second element (2)

5. NULL Pointer:

A pointer that doesn't point to any valid memory location is called a NULL pointer. It's a good practice to initialize pointers to NULL if they are not immediately assigned valid addresses.

int *ptr = NULL;  // Initializing a pointer to NULL

6. Pointers and Functions:

Pointers are often used with functions to achieve tasks like modifying variables outside the function scope or passing arrays efficiently.

void modifyValue(int *x) {
    *x = *x + 10;
}

int main() {
    int num = 5;
    modifyValue(&num);
    printf("Modified value: %d\n", num);  // Prints '15'
    return 0;
}

7. Pointers and Arrays:

Arrays and pointers are closely related in C. In fact, the array name itself can be treated as a pointer to the first element of the array.

int arr[3] = {10, 20, 30};
int *ptr = arr;  // 'ptr' points to the first element of 'arr'

8. Dynamic Memory Allocation:

Pointers are often used in conjunction with dynamic memory allocation functions like malloc, calloc, and free to allocate and deallocate memory during program execution.

int *dynamicArr = (int *)malloc(5 * sizeof(int));
// Use dynamicArr
free(dynamicArr);  // Deallocate the allocated memory

9. Pointer to Functions:

C allows the use of pointers to functions, which enables functions to be assigned to variables and passed as arguments to other functions.

int add(int a, int b) {
    return a + b;
}

int (*ptr)(int, int) = add;  // Pointer to a function
int result = ptr(3, 4);      // Calls the 'add' function through the pointer

10. Pointers and Structures:

Pointers can also be used with structures to access and modify the members of a structure.

struct Point {
    int x;
    int y;
};

struct Point p1 = {10, 20};
struct Point *ptr = &p1;

printf("Coordinates: %d, %d\n", ptr->x, ptr->y);

Understanding pointers is crucial for efficient memory management and manipulation in C. However, improper use of pointers can lead to memory leaks, segmentation faults, and other runtime errors, so it's essential to use them carefully and responsibly.

Command Palette