C语言中的TCP通信服务端例程代码

我可以回答这个问题。以下是一个简单的C语言TCP通信服务端例程代码：

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

#define PORT 8888
#define MAXLINE 1024

int main(int argc, char *argv[]) {
    int listenfd, connfd;
    struct sockaddr_in servaddr, cliaddr;
    socklen_t cliaddr_len;
    char buf[MAXLINE];
    char str[INET_ADDRSTRLEN];
    int i, n;

    listenfd = socket(AF_INET, SOCK_STREAM, 0);
    bzero(&servaddr, sizeof(servaddr));
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(PORT);

    bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
    listen(listenfd, 20);

    printf("Accepting connections ...\n");
    while (1) {
        cliaddr_len = sizeof(cliaddr);
        connfd = accept(listenfd, (struct sockaddr *)&cliaddr, &cliaddr_len);
        inet_ntop(AF_INET, &cliaddr.sin_addr, str, sizeof(str));
        printf("Received a connection from %s\n", str);

        while (1) {
            n = read(connfd, buf, MAXLINE);
            if (n == 0) {
                printf("The client %s closed the connection\n", str);
                break;
            }
            printf("Received message from %s: %s", str, buf);
            for (i = 0; i < n; i++) {
                buf[i] = toupper(buf[i]);
            }
            write(connfd, buf, n);
        }
        close(connfd);
    }
    return 0;
}

这个例程实现了一个简单的TCP通信服务端，监听在8888端口上。当有客户端连接时，服务端会打印出客户端的IP地址，并接收客户端发送的消息，将消息转换为大写后发送回客户端。