一.相关过程以及知识请详见我的另一篇博客《winsock套接字编程》，这里不再累述。
二.相关代码：
server.c：
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1
/****************************************
2 > File Name:server.c
3 > Author:xiaoxiaohui
4 > mail:1924224891@qq.com
5 > Created Time:2016年05月21日 星期六 15时05分23秒
6 ****************************************/
7
8 #include<stdio.h>
9 #include<stdlib.h>
10 #include<sys/types.h>
11 #include<sys/socket.h>
12 #include<unistd.h>
13 #include<arpa/inet.h>
14 #include<netinet/in.h>
15 #include<string.h>
16
17
const
int
PORT = 9090;
18
const
int
LEN = 1024;
19
int
serverSock;
20
struct
sockaddr_in local;
21
struct
sockaddr_in client;
22
23
24
int
main()
25 {
26 serverSock = socket(AF_INET, SOCK_DGRAM, 0);
27
28 local.sin_family = AF_INET;
29
//local.sin_addr.s_addr = htonl(INADDR_ANY);
30 local.sin_port = htons(PORT);
31 local.sin_addr.s_addr = inet_addr(
"127.0.0.1"
);
32 bind(serverSock, (
struct
sockaddr*)&local,
sizeof
(local));
33
34
char
buf[LEN];
35
while
(1)
36 {
37
int
ret = 0;
38 socklen_t len =
sizeof
(client);
39
memset
(buf,
'\0'
, LEN);
40 ret = recvfrom(serverSock, buf, LEN - 1, 0, (
struct
sockaddr*)&client, &len);
41
42
printf
(
"ret is %d"
, ret);
43
if
(ret == 0)
44 {
45
printf
(
"client is closed!\n"
);
46
exit
(2);
47 }
48
else
if
(ret < 0)
49 {
50
perror
(
"recvfrom"
);
51
continue
;
52 }
53
else
54 {
55 buf[ret] =
'\0'
;
56
printf
(
"client[ip:%s][port:%d]# %s\n"
, inet_ntoa(client.sin_addr), \
57 ntohs(client.sin_port), buf);
58
fflush
(stdout);
59 }
60
61
if
(
strstr
(buf,
"quit"
) != NULL)
62 {
63 close(serverSock);
64
return
0;
65 }
66 }
67
return
0;
68 }
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client.c：
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1
/****************************************
2 > File Name:client.c
3 > Author:xiaoxiaohui
4 > mail:1924224891@qq.com
5 > Created Time:2016年05月21日 星期六 15时35分32秒
6 ****************************************/
7
8 #include<stdio.h>
9 #include<sys/types.h>
10 #include<sys/socket.h>
11 #include<unistd.h>
12 #include<arpa/inet.h>
13 #include<netinet/in.h>
14 #include<string.h>
15
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const
int
PORT = 9090;
17
const
char
* IP =
"127.0.0.1"
;
18
//const char* IP = "192.168.0.145";
19
const
int
LEN = 1024;
20
int
clientSock;
21
struct
sockaddr_in server;
22
23
int
main()
24 {
25
26 clientSock = socket(AF_INET, SOCK_DGRAM, 0);
27
28 server.sin_family = AF_INET;
29 server.sin_addr.s_addr = inet_addr(IP);
30 server.sin_port = htons(PORT);
31
32
char
buf[LEN];
33
while
(1)
34 {
35
memset
(buf,
'\0'
, LEN);
36
printf
(
"please input: "
);
37
fflush
(stdout);
38
gets
(buf);
39
40
int
ret = sendto(clientSock, buf,
strlen
(buf), 0, (
struct
sockaddr*)&server,
sizeof
(server));
41
if
(ret <= 0)
42 {
43
perror
(
"sendto"
);
44
continue
;
45 }
46
47
if
(
strcmp
(buf,
"quit"
) == 0)
48 {
49 close(clientSock);
50
return
0;
51 }
52 }
53
54
return
0;
55 }
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Makefile：
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1 .PHONY:all
2 all:server client
3
4 server:server.c
5 gcc -o $@ $^ -g
6 client:client.c
7 gcc -o $@ $^ -g
8
9 .PHONY:clean
10 clean:
11 rm -f server client
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执行结果：
三.总结：
UDP套接字编程是不用建立链接的，所以服务器不用listen和accept，客户端不用connect，recvfrom和sendto中有对方的套接字信息。
UDP因为是面向链接的，所以在传输数据过程中比TCP要高效，适用于流媒体或对可靠性要求不高的应用。
本文转自 ye小灰灰 51CTO博客，原文链接：http://blog.51cto.com/10704527/1782717，如需转载请自行联系原作者
