#include "apue.h"ssize_t             /* Write "n" bytes to a descriptor  */writen(int fd, const void *ptr, size_t n){	size_t		nleft;	ssize_t		nwritten;	nleft = n;	while (nleft > 0) {		if ((nwritten = write(fd, ptr, nleft)) < 0) {			if (nleft == n)				return(-1); /* error, return -1 */			else				break;      /* error, return amount written so far */		} else if (nwritten == 0) {			break;		}		nleft -= nwritten;		ptr   += nwritten;	}	return(n - nleft);      /* return >= 0 */}