/* File: client.c */	#include <sys/types.h>	#include <sys/socket.h>	#include <netinet/in.h>	int main(int argc, char **argv)	{		int fd;		struct sockaddr_in address;		int address_len;		int rtval;		char *data = "Client to Server string!\n";		char data2[100];		int len;		//建立套接口		fd = socket(AF_INET, SOCK_STREAM, 0);		//聯接		address.sin_family = AF_INET;		address.sin_addr.s_addr = inet_addr("127.0.0.1");		address.sin_port = htons(1234);		address_len = sizeof(address);		rtval = connect(fd, (struct sockaddr *)&address, address_len);		if(rtval == -1) exit(1);		//發送數據		writen(fd, (void *)data, strlen(data));		printf("sent line:%s", data);		//接收數據		len = readline(fd, (void *)data2, 100);		printf("readline:%s", data2);		printf("client exit.\n");		//關閉		close(fd);	}