以下是一個簡單的UDP編程實例，用于在Linux系統上發送和接收UDP數據包。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#define BUF_SIZE 1024
void error_handling(char *message);
int main(int argc, char *argv[]) {
int sock;
char message[BUF_SIZE];
int str_len;
socklen_t adr_sz;
struct sockaddr_in serv_adr, from_adr;
if (argc != 3) {
printf("Usage: %s <IP> <port>\n", argv[0]);
exit(1);
}
sock = socket(PF_INET, SOCK_DGRAM, 0);
if (sock == -1)
error_handling("socket() error");
memset(&serv_adr, 0, sizeof(serv_adr));
serv_adr.sin_family = AF_INET;
serv_adr.sin_addr.s_addr = inet_addr(argv[1]);
serv_adr.sin_port = htons(atoi(argv[2]));
while (1) {
fputs("Input message(Q to quit): ", stdout);
fgets(message, BUF_SIZE, stdin);
if (!strcmp(message, "q\n") || !strcmp(message, "Q\n"))
break;
sendto(sock, message, strlen(message), 0, (struct sockaddr *)&serv_adr, sizeof(serv_adr));
adr_sz = sizeof(from_adr);
str_len = recvfrom(sock, message, BUF_SIZE, 0, (struct sockaddr *)&from_adr, &adr_sz);
message[str_len] = 0;
printf("Message from server: %s", message);
}
close(sock);
return 0;
}
void error_handling(char *message) {
fputs(message, stderr);
fputc('\n', stderr);
exit(1);
}

編譯和運行：

$ gcc udp_client.c -o udp_client
$ ./udp_client <IP> <port>

其中，<IP>和<port>是UDP服務器的IP地址和端口號。