#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <pthread.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>void client_p()
{sleep(1);//can use semphorestruct sockaddr_in addr;int sock;if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) < 0){perror("client socket error");return NULL;}addr.sin_family = AF_INET;addr.sin_port = htons(8765);addr.sin_addr.s_addr = inet_addr("127.0.0.1");char buff[10];int n = 0;int len = sizeof(addr);do{n = sendto(sock, "123456789", 10, 0, (struct sockaddr*)&addr, sizeof(sockaddr));if (n < 0){perror("sendto server 1 error");break;}n = recvfrom(sock, buff, 10, 0, (struct sockaddr*)&addr, &len);//ifn = sendto(sock, "987654321", 10, 0, (struct sockaddr*)&addr, sizeof(sockaddr));//if} while (0);close(sock);return NULL;
}
void server_p()
{struct sockaddr_in addr;int sock;if ((sock = socket(AF_INET, SOCK_DGRAM, 0)) < 0){perror("server socket error");return NULL;}addr.sin_family = AF_INET;addr.sin_port = htons(8765);addr.sin_addr.s_addr = inet_addr("127.0.0.1");char buff[10];int n = 0;int len = sizeof(addr);do{if (bind(sock, (struct sockaddr*)&addr, len) < 0){perror("bind error");break;}n = recvfrom(sock, buff, 4, 0, (struct sockaddr*)&addr, &len);if (n < 0){perror("recvfrom client 1 error");break;}else {printf("recv 1:%s\n", buff);//buff is a string
        }n = sendto(sock, "1", 1, 0, (struct sockaddr*)&addr, sizeof(sockaddr));//if (n < 0)n = recvfrom(sock, buff, 4, 0, (struct sockaddr*)&addr, &len);if (n < 0){perror("recvfrom client 2 error");break;}else{printf("recv 2:%s\n", buff);//buff is a string
        }} while (0);close(sock);return NULL;
}
int main(int argc, char**argv)
{int ret = 0;pthread_t client, server;ret = pthread_create(&server, NULL, (void*)server_p, NULL);//ifret = pthread_create(&client, NULL, (void*)client_p, NULL);//if
    pthread_join(server);pthread_join(client);return 0;
}