client.c

此程序为linux下的socket编程

#include <stdio.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <string.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <string.h>
#include  <errno.h>
#include <sys/time.h>

#define PORT 3490  
#define MAXDATASIZE 100 /*每次最大数据传输量 */  
int main(int argc, char *argv[])  
{  
	int sockfd, numbytes;  
	char buf[MAXDATASIZE];  
	struct hostent *he;  
	struct sockaddr_in their_addr;  
	if (argc != 2) 
		{  
			fprintf(stderr,"usage: client hostname ");
			 exit(1); 
		}  
	if((he=gethostbyname(argv[1]))==NULL) 
		{  
			herror("gethostbyname"); 
			exit(1); 
		}  
	if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) 
		{  
			perror("socket"); exit(1); 
		}  
	their_addr.sin_family=AF_INET;  
	their_addr.sin_port=htons(PORT);  
	their_addr.sin_addr = *((struct in_addr *)he->h_addr);  
	bzero(&(their_addr.sin_zero),8);  
	if (connect(sockfd, (struct sockaddr *)&their_addr,sizeof(struct sockaddr)) == -1) 
		{/*错误检测*/  
			perror("connect"); 
			exit(1); 
		}  
	if ((numbytes=recv(sockfd, buf, MAXDATASIZE, 0)) == -1) 
		{  
			perror("recv"); 
			exit(1); 
		}  
	buf[numbytes] = ' ';  
  printf("Received: %s\r\n",buf);  
	close(sockfd);  
  return 0;  
}