在C中编译套接字连接代码时出现问题

struct hostent *lh               = gethostbyname(hostname);

int socketDescriptor             = socket(AF_INET,SOCK_STREAM, 0);

sockaddr_in socketInfo;

memset(&socketInfo, 0, sizeof(socketInfo));
socketInfo.sin_family            = AF_INET;
socketInfo.sin_addr.s_addr       = ((in_addr *)(lh->h_addr))->s_addr;
socketInfo.sin_port              = htons(portNumber);

connect(socketDescriptor,&socketInfo,sizeof(socketInfo));
struct hostent *lh               = gethostbynam