13.7.1. Problem

13.7.2. Solution

13.7.3. Discussion

There are two ways to do this. Here's the faster method:

$pattern = "/\bo'reilly\b/i"; // only O'Reilly books
$ora_books = preg_grep($pattern, file('/path/to/your/file.txt'));

Here's the more efficient method:

$fh = fopen('/path/to/your/file.txt', 'r') or die($php_errormsg);
while (!feof($fh)) {
    $line = fgets($fh, 4096);
    if (preg_match($pattern, $line)) { $ora_books[ ] = $line; }
}
fclose($fh);

Since the first method reads in everything all at once, it's about three times faster then the second way, which parses the file line by line but uses less memory. One downside, however, is that because the regular expression works only on one line at a time, the second method doesn't find strings that span multiple lines.

13.7.4. See Also