tcp_echo_cli.c

linux下的多个网络通讯的例子 可多参考下

/*
 * TCP 客户端演示代码
 */                                     
#include <stdio.h>                                    
#include <stdlib.h>                                   
#include <errno.h>                                    
#include <string.h>                                   
#include <netdb.h>                                    
#include <sys/types.h>                                
#include <netinet/in.h>                               
#include <sys/socket.h>  

#define MYPORT 4950  
	
int main(int argc,char *argv[]) {                     
		int sockfd,numbytes;                                  
		char buf[100];                                        
		struct hostent *he;                                   
		struct sockaddr_in their_addr;                        
		
		unsigned short port;
		int i = 0;            
		
		
		if (argc != 4) {                                                              
        fprintf(stderr,"usage: talker hostname message port\n");                       
        exit(1);                                                                  
    }     
    
    port = (unsigned short ) atoi(argv[3]);  
		
		   /* 尝试做一下域名转换*/                                                                                
		    if ((he=gethostbyname(argv[1])) == NULL) {  /* get the host info */           
		        perror("gethostbyname");                                                  
		        exit(1);                                                                  
		    }  
		       
		
		                      
		//第一步:建立一个TCP套接字                                   
		if((sockfd = socket(AF_INET,SOCK_STREAM,0))==-1) {    
			perror("socket");                                     
			exit(1);                                              
		}      
		
		
		
		                                               
		//第二步:设置服务器地址和端口2323
		// 
		memset(&their_addr,0,sizeof(their_addr)); 
		               
		their_addr.sin_family = AF_INET;                      
		their_addr.sin_port = htons(port);                    
		their_addr.sin_addr.s_addr = inet_addr(argv[1]);	
	//	their_addr.sin_addr.s_addr = inet_addr("192.168.0.146");	
	//	their_addr.sin_addr.s_addr = *((struct in_addr *)he->h_addr); 
		memset(&(their_addr.sin_zero),0,8);	
		
		
		printf("connect server %s:%d\n",argv[1],port);
		
		                   
		//第三步:用connect 和服务器建立连接 ,
		 //注意,这里没有使用本地端口,将由协议栈自动分配一个端口                                   
		if(connect(sockfd,(struct sockaddr *)&their_addr,sizeof(struct sockaddr))==-1){                                                
			perror("connect");                                    
			exit(1);                                              
		}                                                     
		//第四步,向服务器发送字符串"hello!"   
		strcpy(buf,argv[2]);                       
		if(send(sockfd,buf,6,0)==-1) {                   
			perror("send");                                       
			exit(1);                                              
		}                                                     
		//第五步:接受从服务器返回的信息                              
		if((numbytes = recv(sockfd,buf,100,0))==-1) {         
			perror("recv");                                       
			exit(1);                                              
		}                                                     
		buf[numbytes] = 0;                                   
		printf("result:%s\n",buf);   
		
		//第六步,关闭网络联接                           
		close(sockfd);                                        
		return 0;                                             
}