Impara What Is a Socket | Networking Foundations in C

Prerequisiti

C Basics

Definition

Sockets are essential for network communication in C. A socket is an endpoint that lets a program send and receive data over a network. It provides a standard method for exchanging information between computers, forming the basis of most networked applications.

In C, sockets are created using the socket() system call. This function allows you to specify the communication domain (such as IPv4 or IPv6), the socket type (such as stream or datagram), and the protocol (like TCP or UDP). By correctly setting up these parameters, you control how your application will communicate over the network.

Understanding how to create and configure a socket is the first step toward building any networked application in C. You will use sockets to connect, send, and receive data, whether you are writing a client or a server.

simple_socket.c


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#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>

int main() {
    // Create a socket: domain = AF_INET (IPv4), type = SOCK_STREAM (TCP), protocol = 0 (default)
    int sockfd = socket(AF_INET, SOCK_STREAM, 0);

    if (sockfd == -1) {
        perror("socket");
        return 1;
    }

    printf("Socket created successfully! File descriptor: %d\n", sockfd);

    // Normally, you would use the socket here (bind, connect, etc.)
    // For this example, just close it.
    close(sockfd);

    return 0;
}

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Sezione 1. Capitolo 1

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