UDP编程·client

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <pthread.h>


#define portnumber 2333
int main(int argc,char * argv[])
{
    int sockfd;
struct sockaddr_in server_addr;
struct hostent * host;


if(argc != 2)
{
   printf("The paramemter is wrong.\n");
exit(-1);
}


  if((host = gethostbyname(argv[1])) == NULL)
{
fprintf(stderr,"Gethostbyname Failed : %s\n ",strerror(errno));
exit(-1);
}


if((sockfd = socket(AF_INET,SOCK_DGRAM,0)) < 0)
{
   fprintf(stderr,"Socket Failed : %s\n",strerror(errno));
exit(-1);
}


    bzero(&server_addr,sizeof(struct sockaddr_in));
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(portnumber);
//server_addr.sin_addr.s_addr = inet_addr(argv[1]);
server_addr.sin_addr = *((struct in_addr *)host->h_addr);

bind(sockfd,(struct sockaddr *)(&server_addr),sizeof(struct sockaddr_in));

char buffer[1024];
fgets(buffer,1024,stdin);

int nwrite = sendto(sockfd, buffer, 1024,0,(struct sockaddr*)&server_addr,sizeof(server_addr));
memset(buffer,0,sizeof(buffer));


int nread = -1;
struct sockaddr_in cli_addr;
socklen_t len = sizeof(cli_addr);

if((nread = recvfrom(sockfd,buffer,1024,0,(struct sockaddr *)(&cli_addr),&len)) > 0)
{
   printf("%s\n",buffer);
memset(buffer,0,sizeof(buffer));
}

return 0;
}