How to use network programming functions in C++?

How to use network programming functions in C?

In modern society, the Internet has become an indispensable part of people's lives. In the field of software development, network programming is an important part of it. As a powerful programming language, C provides a wealth of network programming functions and libraries, allowing developers to easily build various network applications. This article introduces some commonly used C network programming functions and demonstrates how to use them.

In C, network programming mainly uses sockets for communication. A socket is an abstract concept used for network communication through which data can be sent and received. C provides the socket function for creating sockets. The prototype of this function is:

int socket(int domain, int type, int protocol);

Among them, the domain parameter specifies the protocol family used, common ones include AF_INET (IPv4) and AF_INET6(IPv6). The type parameter specifies the type of socket, which can be SOCK_STREAM (for connection-oriented reliable data transmission, such as TCP) or SOCK_DGRAM (for no Unreliable data transfer over connections such as UDP). The protocol parameter specifies the specific protocol used, which can be 0 (automatically selected) or a specific protocol number.

The following is a simple example showing how to create a TCP socket:

#include <iostream>
#include <sys/socket.h>

int main() {
    int sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd == -1) {
        std::cout << "Failed to create socket" << std::endl;
        return 1;
    }
    
    std::cout << "Socket created successfully" << std::endl;
    
    // 后续可以继续在该套接字上进行数据通信操作
    
    return 0;
}

After creating the socket, we can use the bind function to A socket is bound to a specific IP address and port, thereby specifying the local network interface. The prototype of the bind function is as follows:

int bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen);

sockfdThe parameter is the socket descriptor, and the addr parameter is a sockaddrStructure pointer, which contains IP address and port number information. The addrlen parameter specifies the length of the addr structure.

Here is an example showing how to bind a socket to a local IP address and port number:

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

int main() {
    int sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd == -1) {
        std::cout << "Failed to create socket" << std::endl;
        return 1;
    }
    
    struct sockaddr_in addr;
    addr.sin_family = AF_INET;
    addr.sin_port = htons(8080); // 使用端口号8080
    addr.sin_addr.s_addr = INADDR_ANY; // 使用本地的IP地址
    
    if (bind(sockfd, (struct sockaddr*)&addr, sizeof(addr)) == -1) {
        std::cout << "Failed to bind socket" << std::endl;
        return 2;
    }
    
    std::cout << "Socket bound successfully" << std::endl;
    
    // 后续可以继续在该套接字上进行数据通信操作
    
    return 0;
}

After the binding is complete, we can use listenThe function sets the socket to listening mode to receive connection requests from other hosts. listenThe prototype of the function is as follows:

int listen(int sockfd, int backlog);

sockfdThe parameter is the socket descriptor, and the backlog parameter specifies the waiting for connection in the connection queue the maximum number. Once the client initiates a connection request, the server can accept the connection through the accept function. The prototype of the accept function is as follows:

int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen);

sockfdThe parameter is the socket descriptor, and the addr parameter is a sockaddrStructure pointer, used to save the client's address information. The addrlen parameter is the length of the addr structure.

The following is an example that shows how to accept connections from the client on the server side:

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

int main() {
    int sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd == -1) {
        std::cout << "Failed to create socket" << std::endl;
        return 1;
    }
    
    struct sockaddr_in addr;
    addr.sin_family = AF_INET;
    addr.sin_port = htons(8080); // 使用端口号8080
    addr.sin_addr.s_addr = INADDR_ANY; // 使用本地的IP地址
    
    if (bind(sockfd, (struct sockaddr*)&addr, sizeof(addr)) == -1) {
        std::cout << "Failed to bind socket" << std::endl;
        return 2;
    }
    
    if (listen(sockfd, 5) == -1) {
        std::cout << "Failed to listen on socket" << std::endl;
        return 3;
    }
    
    std::cout << "Waiting for incoming connections..." << std::endl;
    
    struct sockaddr_in client_addr;
    socklen_t client_addrlen = sizeof(client_addr);
    
    int client_sockfd = accept(sockfd, (struct sockaddr*)&client_addr, &client_addrlen);
    if (client_sockfd == -1) {
        std::cout << "Failed to accept client connection" << std::endl;
        return 4;
    }
    
    std::cout << "Client connected successfully" << std::endl;
    
    // 后续可以继续在该客户端套接字上进行数据通信操作
    
    return 0;
}

The above example only shows a small part of the use of network programming functions in C. C provides more powerful functions and libraries to meet the different needs of developers. I hope that by reading this article, readers will have a preliminary understanding of network programming functions in C and be able to apply relevant knowledge in actual development. Network programming is a broad and in-depth field that requires continuous learning and practice. I hope readers can achieve more results through continuous exploration.

The above is the detailed content of How to use network programming functions in C++?. For more information, please follow other related articles on the PHP Chinese website!