The documentation page on glob() has this example:
<?php
foreach (glob("*.txt") as $filename) {
echo "$filename size " . filesize($filename) . "
";
}
?>
But to be honest, I don't understand how this can work.
The array produced by glob("*.txt") will be traversed, but where does this array come from? Is glob() reading a directory? I don't see that anywhere in the code. Glob() looks for all matches to *.txt
But where do you set where the glob() function should look for these strings?
Without any directory specified glob() would act on the current working directory (often the same directory as the script, but not always).
To make it more useful, use a full path such as glob("/var/log/*.log"). Admittedly the PHP documentation doesn't make the behaviour clear, but glob() is a C library function, which is where it originates from.
Yes, glob reads the directory. Therefore, if you are looking to match files in a specific directory, then the argument you supply to glob() should be specific enough to point out the directory (ie "/my/dir/*.png"). Otherwise, I believe that it will search for files in the 'current' directory.
Note that on some systems filenames can be case-sensitive so "*.png" may not find files ending in ".PNG".
A general overview of its purpose can be found here. Its functionality in PHP is based on that of the libc glob function whose rationale can be read at http://web.archive.org/web/20071219090708/http://www.isc.org/sources/devel/func/glob.txt .
Something useful I've discovered with glob(), if you want to traverse a directory, for example, for images, but want to match more than one file extension, examine this code.
$images = glob($imagesDir . '*' . '.{jpg,jpeg,png,gif}', GLOB_BRACE);
The GLOB_BRACE flag makes the braces sort of work like the (a|b) regex.
One small caveat is that you need to list them out, so you can't use regex syntax such as jpe?g to match jpg or jpeg.