Linux UDP通信中sendto和recvfrom函数怎么用

#include <sys/socket.h>

ssize_t sendto(int sockfd, const void *buf, size_t len, int flags,
               const struct sockaddr *dest_addr, socklen_t addrlen);

struct sockaddr_in dest_addr;
memset(&dest_addr, 0, sizeof(dest_addr));

dest_addr.sin_family = af_inet;
dest_addr.sin_port = htons(8888);         // 主机端口转网络大端
inet_aton("127.0.0.1", &dest_addr.sin_addr); // 字符串ip转网络大端

char msg[] = "hello udp";
ssize_t ret = sendto(sockfd, msg, strlen(msg), 0,
                     (struct sockaddr *)&dest_addr, sizeof(dest_addr));
if(ret == -1)
{
    perror("sendto failed");
}

ssize_t recvfrom(int sockfd, void *buf, size_t len, int flags,
                 struct sockaddr *src_addr, socklen_t *addrlen);

char buf[1024] = {0};
struct sockaddr_in client_addr;
socklen_t addr_len = sizeof(client_addr);

ssize_t n = recvfrom(sockfd, buf, sizeof(buf)-1, 0,
                     (struct sockaddr *)&client_addr, &addr_len);
if(n > 0)
{
    buf[n] = '\0';
    // 网络字节序转主机字节序打印
    printf("收到消息：%s，来自 %s:%d\n",
           buf,
           inet_ntoa(client_addr.sin_addr),
           ntohs(client_addr.sin_port));
}