How to use C++ function library for network programming?

Network programming in C libraries provides functions such as socket API, Boost.Asio and Qt Network through libraries. The practical case shows the steps to build a TCP server using the Berkeley Socket API: 1. Include header files; 2. Create sockets; 3. Bind sockets to addresses and ports; 4. Listen for connections; 5. Process clients end request.

Network Programming in C Library

Introduction

Network programming involves using Computers send and receive data on the network. The C library provides powerful networking capabilities, allowing developers to easily build network applications. This article will introduce how to use libraries for network programming in C and provide a practical case.

Library Overview

• Sockets API (Berkeley Sockets): Provides low-level network access.
• Boost.Asio: A cross-platform, asynchronous network library.
• Qt Network: Part of the Qt framework, providing platform-independent network functionality.

Practical case: Building a TCP server

This example demonstrates the steps to build a simple TCP server using the Berkeley socket API:

1. Include the header file

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

2. Create the socket

int server_sockfd = socket(AF_INET, SOCK_STREAM, 0);

• AF_INET represents IPv4.
• SOCK_STREAM Represents a TCP socket.
• 0 represents the default protocol.

3. Bind the socket to the address and port

sockaddr_in server_addr;
server_addr.sin_family = AF_INET;
server_addr.sin_addr.s_addr = htonl(INADDR_ANY);
server_addr.sin_port = htons(PORT);

bind(server_sockfd, (struct sockaddr*) &server_addr, sizeof(server_addr));

• INADDR_ANY Make the server listen on all interfaces connect.
• PORT is the port number to listen on.

4. Listen for connections

int client_sockfd = accept(server_sockfd, NULL, NULL);

• accept() Block until a client connects.
• Returns a new socket descriptor client_sockfd associated with the client.

5. Handle client requests

while (true) {
  char buffer[BUFSIZ];
  int bytes_received = recv(client_sockfd, buffer, BUFSIZ, 0);
  // 处理接收到的数据
}

• recv() Receive data from the client.
• buffer is the buffer used to store received data.
• BUFSIZ is the maximum size of the buffer.

Conclusion

This article showed how to use C libraries for network programming. The Berkeley Sockets API is a low-level approach that provides direct access to the network. Boost.Asio and Qt Network provide higher-level asynchronous and cross-platform capabilities.

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