/*** client.c -- a stream socket client demo*/#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <errno.h>#include <string.h>#include <netdb.h>#include <sys/types.h>#include <netinet/in.h>#include <sys/socket.h>#define PORT 3490 // the port client will be connecting to #define MAXDATASIZE 100 // max number of bytes we can get at once int main(int argc, char *argv[]){    int sockfd, numbytes;      char buf[MAXDATASIZE];    struct hostent *he;    struct sockaddr_in their_addr; // connector's address information     if (argc != 2) {        fprintf(stderr,"usage: client hostname\n");        exit(1);    }    if ((he=gethostbyname(argv[1])) == NULL) {  // get the host info         perror("gethostbyname");        exit(1);    }    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {        perror("socket");        exit(1);    }    their_addr.sin_family = AF_INET;    // host byte order     their_addr.sin_port = htons(PORT);  // short, network byte order     their_addr.sin_addr = *((struct in_addr *)he->h_addr);    memset(&(their_addr.sin_zero), '\0', 8);  // zero the rest of the struct     if (connect(sockfd, (struct sockaddr *)&their_addr, sizeof(struct sockaddr)) == -1) {        perror("connect");        exit(1);    }    if ((numbytes=recv(sockfd, buf, MAXDATASIZE-1, 0)) == -1) {        perror("recv");        exit(1);    }    buf[numbytes] = '\0';    printf("Received: %s",buf);    close(sockfd);    return 0;}