Multithreading in C - A Primer for Beginners


Multithreading is a powerful concept in C programming that allows you to run multiple threads of execution concurrently. This guide provides an introduction to multithreading in C for beginners and includes sample code to help you get started.

What is Multithreading?

Multithreading is a technique that enables a program to execute multiple threads concurrently. Threads are lightweight processes within a program that share the same memory space, allowing them to communicate and work together efficiently.

Why Use Multithreading?

Multithreading is used for various purposes, including:

  • Improving program performance by taking advantage of multiple CPU cores.
  • Enhancing responsiveness in user interfaces by keeping the application responsive while performing time-consuming tasks in the background.
  • Implementing parallel processing for tasks that can be divided into smaller subtasks that run concurrently.

Sample Code - Creating a Simple Thread

Let's create a simple C program that demonstrates the creation and execution of a separate thread.

#include <stdio.h>
#include <pthread.h>
// Function to be executed by the new thread
void *threadFunction(void *arg) {
int threadID = *((int *)arg);
printf("Hello from Thread %d\n", threadID);
return NULL;
int main() {
// Number of threads to create
int numThreads = 4;
// Create an array to store thread IDs
pthread_t threads[numThreads];
int threadArgs[numThreads];
// Create and execute multiple threads
for (int i = 0; i < numThreads; i++) {
threadArgs[i] = i;
pthread_create(&threads[i], NULL, threadFunction, &threadArgs[i]);
// Wait for threads to finish
for (int i = 0; i < numThreads; i++) {
pthread_join(threads[i], NULL);
printf("All threads have finished.\n");
return 0;


Multithreading is a fundamental concept in C programming that allows you to harness the power of concurrency. With multithreading, you can improve program performance, responsiveness, and parallel processing capabilities. The sample code provided demonstrates how to create and run multiple threads in a C program. As you continue to explore multithreading, you'll discover more advanced techniques and applications.