(1) client端，发数据：

udp_client.c文件

#include

#include

#include

#include

#include

#include

#include

#include

#include

#define SIZE 100

int main(int argc, char **argv){

int sd;

struct sockaddr_in server;

struct hostent *hp;

char *temp_buf;

char *address;

temp_buf = (char *)malloc(sizeof(char) * SIZE);

temp_buf[0] = 'a';

temp_buf[1] = 'b';

sd = socket(AF_INET, SOCK_DGRAM, 0);

server.sin_family = AF_INET;

server.sin_port = htons(12345);

address = "127.0.0.1";

inet_pton(AF_INET, address, &server.sin_addr);

for(;;){

sendto(sd, temp_buf, strlen(temp_buf), 0, (struct sockaddr *) &server, sizeof(server));

sleep(2);

}

close(sd);

}

(2) server端，接收数据：
udp_server.c文件
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define SIZE 100
#define MAXLINE 256
int main(int argc, char **argv){
int n, sd;
struct sockaddr_in server, send_addr;
char recv_buf[MAXLINE];
char *temp_buf;
temp_buf = (char *)malloc(sizeof(char) * SIZE);
server.sin_family = AF_INET;
server.sin_addr.s_addr = htonl(INADDR_ANY);
server.sin_port = htons(12345);
sd = socket(AF_INET, SOCK_DGRAM, 0);
bind(sd, (struct sockaddr *)&server, sizeof(server));
for(;;){
n = recvfrom(sd, recv_buf, MAXLINE, 0, (struct sockaddr *)&send_addr, (socklen_t *) sizeof(send_addr));
printf("Received: %s\n", recv_buf);
}

close(sd);
return 0;
}