socket udp server clinet

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <netinet/in.h>
#define SERVPORT 3333
#define BACKLOG 10
#define MAX_CONNECTED_NO 100
#define MAXDATASIZE 100
int main()
{
	struct sockaddr_in server_sockaddr,client_sockaddr;
	int sin_size,recvbytes;
	int sockfd,client_fd;
	char buf[MAXDATASIZE];
	if((sockfd=socket(AF_INET,SOCK_DGRAM,0))==-1)
	{
		perror("socket");
		exit(1);
	}
	printf("socket success!,sockfd=%d\n",sockfd);
	server_sockaddr.sin_family=AF_INET;
	server_sockaddr.sin_port=htons(SERVPORT);
	server_sockaddr.sin_addr.s_addr=INADDR_ANY;
	bzero(&(server_sockaddr.sin_zero),8);
	if(bind(sockfd,(struct sockaddr *)&server_sockaddr,sizeof(struct sockaddr))==-1)
	{
		perror("bind");
		exit(1);
	}
	printf("bind success!\n");
	while(1){	
	if((recvbytes=recv(sockfd,buf,MAXDATASIZE,0))==-1)
	{
		perror("recv");
		exit(1);
	}
	printf("received a connection:%s\n",buf);
	}
	close(sockfd);
}

#include<sys/types.h>
#include<sys/socket.h>
#include<errno.h>
#include<string.h>
#include<netinet/in.h>
#include<stdio.h>
#include<stdlib.h>
#include<netdb.h>
#define SERVERPORT 3333
#define MAXDATASIZE 100
main(int argc,char *argv[]){
	int sockfd,sendbytes;
	char buf[MAXDATASIZE];
	struct hostent *host;
	struct sockaddr_in serv_addr;
	if(argc<2)
	{
		fprintf(stderr,"please enter the server's hostname!\n");
		exit(1);
	}

	if((host=gethostbyname(argv[1]))==NULL)
	{
		perror("socket");
		exit(1);
	}

	if((sockfd=socket(AF_INET,SOCK_DGRAM,0))==-1)
	{
		perror("socket");
		exit(1);
	}

	serv_addr.sin_family=AF_INET;
	serv_addr.sin_port=htons(SERVERPORT);
	serv_addr.sin_addr=*((struct in_addr *)host->h_addr);
	bzero(&(serv_addr.sin_zero),8);
	
	if(connect(sockfd,(struct sockaddr *)&serv_addr,sizeof(struct sockaddr))==-1)
	{
		perror("connect");
		exit(1);	
	}
	char a[100];
	gets(a);
	printf("%s\n",a);
	printf("%d\n",sizeof(a));
	if((sendbytes=send(sockfd,a,sizeof(a),0))==-1){
		perror("send");
		exit(1);
	}
	close(sockfd);
}