ZEND PHP 5 Certification STUDY GUIDE

Streams and Network Programming ” 239
Accessing Files
PHP provides several different ways to create, read from and write to files, depending
on the type of operation that you need to perform. First up, we have the more
traditional, C-style functions. Just like their C counterparts, these open/create, read,
write and close a file handle. A file handle is a reference to an external resource—this
means you are not loading the entire file into memory when manipulating it, but
simply dealing with a reference to it. Thus, this family of functions is very resource
friendly and—while considered somewhat antiquated and arcane in comparison to
some of the more recent additions to PHP—is still best-practice material when it
comes to dealing with large files:
$file = fopen("counter.txt", ’a+’);
if ($file == false) {
die ("Unable to open/create file");
}
if (filesize("counter.txt") == 0) {
$counter = 0;
} else {
$counter = (int) fgets($file);
}
ftruncate($file, 0);
$counter++;
fwrite($file, $counter);
echo "There has been $counter hits to this site.";
In this example, we start by opening the file using fopen(); we will use the resulting
resource when calling every other function that will work with our file. Note that
fopen() returns false upon failure—and we must check for it explicitly to ensure
that PHP doesn’t play any automatic-conversion tricks on us.
Next up, we use filesize() to make sure that the file is not empty and our counter
has been started. If it is empty, we set the counter to 0; otherwise, we grab the first
Licensed to 482634 - Amber Barrow (itsadmin@deakin.edu.au)