client.c

该系统是linux下的socket编程

/*
// 客户端发送两个随机数到服务器，服务器返回结果
*/

#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/socket.h>
#include <resolv.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <time.h>
#define MAX_BUF			1024

/*产生随机数*/

int getrandom()
{
	return 2+(int) (100.0*rand()/(RAND_MAX+5.0));   
}
int main(int argc,char ** argv)
{
	int sockfd,len;
	int num1,num2,i,result;
	struct sockaddr_in server_addr;
	char buf[MAX_BUF+1];
	char temp[MAX_BUF+1];
	
	if (argc!=3)
	{
		printf("parameter format error!\n
			correct usage is:%s IP address Port\n
			ex:\t%s 127.0.0.1 80\n"
			,argv[0],argv[0]);
		exit(1);
	}
	/*创建socket*/
	if ((sockfd = socket(AF_INET,SOCK_STREAM,0))==-1)
	{
		perror("create socket error!\n");
		exit(1);
	} 
	else
	{
		printf("socket created!\n");
	}

	/* 初始化服务器端（对方）的地址和端口信息 */
	bzero(&server_addr,sizeof(server_addr));
	server_addr.sin_family = AF_INET;
	server_addr.sin_port = htons(atoi(argv[2]));
	if (inet_aton(argv[1], (struct in_addr *) &server_addr.sin_addr.s_addr) == 0) 
	{
		perror(argv[1]);
		exit(1);
	}

	/*连接服务器*/
	if (connect(sockfd,(struct sockaddr*)&server_addr,sizeof(server_addr))==-1)
	{
		perror("connect error!\n");
		exit(1);
	} 
	else
	{
		printf("server connected!\n");
	}
	/*产生两个随机数，发送到服务器端*/
	bzero(&buf,MAX_BUF+1);
	srand((unsigned)time(NULL));
	num1 = getrandom();
	num2 = getrandom();
	sprintf(buf,"%d%s%d",num1,"@",num2);
	len = send (sockfd,buf,sizeof(buf),0);
	if (len<=0)
	{
		printf("message sending failed!\n");
		exit(1);
	} 
	else
	{
		printf("successfully sended two numbers:%d %d\n",num1,num2);
	}
	/*从服务器返回的消息中取出结果*/
	bzero(&buf,MAX_BUF+1);
	len = recv(sockfd,buf,MAX_BUF,0);
	
	if (len>0)
	{
		for (i = 0; i<MAX_BUF;i++)
		{
			if (buf[i]!='@')
			{
				temp[i] = buf[i];
			}
			else
				break;
		}
		result = atoi(&buf[i+1]);
		printf("receive result from %s:%d\n",temp,result);
	} 
	else
	{
		printf("receive error!\n");
		exit(1);
	}
	close(sockfd);
	return 0;
}