UDP编程入门

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udp函数:
头文件: #include  #include

int sendto(int sockfd, const void *msg,int len,unsigned int flags,const struct sockaddr *to, int tolen);
　　该函数比send()函数多了两个参数，to表示目地机的IP地址和端口号信息，而tolen常常被赋值为sizeof (struct sockaddr)。Sendto 函数也返回实际发送的数据字节长度或在出现发送错误时返回-1。
　Recvfrom()函数原型为：
　　int recvfrom(int sockfd,void *buf,int len,unsigned int flags,struct sockaddr *from,int *fromlen);
　　from是一个struct sockaddr类型的变量，该变量保存源机的IP地址及端口号。fromlen常置为sizeof(struct sockaddr)。当recvfrom()返回时，fromlen包含实际存入from中的数据字节数。Recvfrom()函数返回接收到的字节数或当出现错误时返回-1，并置相应的errno。
以下为服务端程序:
#include
#include
#include
#include
#include
#include
#include
#include
#include
int port = 8888;
int main()
{
int sockfd;
int len;
int z;
char buf[256];
struct sockaddr_in adr_inet;
struct sockaddr_in adr_clnt;

printf("wait client.....\n");

adr_inet.sin_family = AF_INET;
adr_inet.sin_port = htons(port);
adr_inet.sin_addr.s_addr = htonl(INADDR_ANY);
bzero(&(adr_inet.sin_zero), 8);
len = sizeof(adr_clnt);

sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if (sockfd == -1)
{
  perror("create socket error");
  exit(1);
}
z = bind(sockfd, (struct sockaddr *)&adr_inet, sizeof(adr_inet));
if (z == -1)
{
  perror("bind error");
  exit(1);
}
while (1)
{
  z = recvfrom(sockfd, buf, sizeof(buf), 0, (struct sockaddr *)&adr_clnt, &len);
  if (z

以下为客户端程序:

#include
#include
#include
#include
#include
#include
#include
#include
#include
int port = 8888;

int main()
{
int sockfd;
int i = 0;
int z;

char buf[80], str1[80];
struct sockaddr_in adr_srvr;
FILE *fp;
printf("open file......\n");
fp = fopen("liu", "r");
if (fp == NULL)
{
  perror("open file error");  
  exit(1);
}
printf("connect serve.....\n");
adr_srvr.sin_family = AF_INET;
adr_srvr.sin_port = htons(port);
adr_srvr.sin_addr.s_addr = htonl(INADDR_ANY);
bzero(&(adr_srvr.sin_zero), 8);
sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if (sockfd == -1)
{
  perror("socket error");
  exit(1);
}
printf("send file.....\n");
for (i = 0; i
建立文件liu

打开一个终端:运行服务程序
[root@localhost net]# ./udp_s
wait client.....


打开另一个终端,运行客户端程序

[root@localhost net]# ./udp_c
open file......
connect serve.....
send file.....
0: hello linux
1: hello world
2: nice to me you
send ........
[root@localhost net]#
服务端显示:
[root@localhost net]# ./udp_s
wait client.....
receive: 0: hello linux
receive: 1: hello world
receive: 2: nice to me you
receive: stop
end........
[root@localhost net]#


本文来自ChinaUnix博客，如果查看原文请点：http://blog.chinaunix.net/u2/86974/showart_2155100.html