C Socket Examples 🎯

Welcome to our in-depth guide on C Socket Programming! This tutorial is designed for both beginners and intermediate learners who want to understand and implement socket programming in C. Let's dive in!

Understanding Socket Programming 📝

Socket programming is a method of communication between two devices over a network. It allows your C programs to send and receive data over the internet.

Why use Socket Programming? 💡

It enables communication between applications running on different hosts.
It's versatile and can be used for various network protocols such as TCP, UDP, etc.
It's the foundation for many real-world applications like file transfer, email, web browsing, and more!

Getting Started with C Sockets 🎯

To work with sockets in C, we need to include the following header files:

socket.h: Contains various socket-related functions
netinet/in.h: Contains the sockaddr_in structure
arpa/inet.h: Contains the inet_addr() function

Creating a Simple Socket Program 📝

Let's create a simple client-server example to understand the basics.

Server Code

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

int main() {
    int server_fd, new_socket;
    struct sockaddr_in address;
    int opt = 1;
    int addrlen = sizeof(address);
    char buffer[1024] = {0};
    char* message = "Hello from the server";

    // Create socket
    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {
        perror("socket failed");
        exit(EXIT_FAILURE);
    }

    // Set options on the socket
    if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR | SO_REUSEPORT, &opt, sizeof(opt))) {
        perror("setsockopt");
        exit(EXIT_FAILURE);
    }

    // Define the server address
    address.sin_family = AF_INET;
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_port = htons(8888);

    // Bind the socket to the specified address and port
    if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }

    // Listen for incoming connections
    if (listen(server_fd, 3) < 0) {
        perror("listen");
        exit(EXIT_FAILURE);
    }

    // Accept an incoming connection
    if ((new_socket = accept(server_fd, (struct sockaddr *)&address, (socklen_t*)&addrlen)) < 0) {
        perror("accept");
        exit(EXIT_FAILURE);
    }

    // Receive data from the client
    read(new_socket, buffer, 1024);
    printf("Received: %s\n", buffer);

    // Send a response to the client
    send(new_socket, message, strlen(message), 0);

    return 0;
}

Client Code

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>

int main() {
    int sock = 0, valread;
    struct sockaddr_in serv_addr;
    char* message = "Hello from the client";
    char buffer[1024] = {0};

    // Create socket
    if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        perror("socket creation error");
        exit(EXIT_FAILURE);
    }

    // Define the server address
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(8888);

    // Convert IPv4 address from text to binary form
    if (inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr) <= 0) {
        perror("invalid address/ address not supported");
        exit(EXIT_FAILURE);
    }

    // Connect to the server
    if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {
        perror("connection failed");
        exit(EXIT_FAILURE);
    }

    // Send data to the server
    send(sock, message, strlen(message), 0);

    // Receive a response from the server
    valread = read(sock, buffer, 1024);
    printf("Received: %s\n", buffer);

    return 0;
}

Quiz Time 🎯

Happy learning, and we hope you enjoyed our deep dive into C Socket Programming! Stay tuned for more practical tutorials on CodeYourCraft. 🎯