Getting a List of Filenames Matching a Pattern






Getting a List of Filenames Matching a Pattern

Problem

You want to find all filenames that match a pattern.

Solution

Use a FilterIterator subclass with DirectoryIterator. The FilterIterator subclass needs its own accept( ) method that decides whether or not a particular value is acceptable. The code in Figure only accepts filenames that end with common extensions for images.

Using a FilterIterator

<?php
class ImageFilter extends FilterIterator {
    public function accept() {
        return preg_match('@\.(gif|jpe?g|png)[email protected]',$this->current());
    }
}
foreach (new ImageFilter(new DirectoryIterator('/usr/local/images')) as $img) {
    print "<img src='".htmlentities($img)."'/>\n";
}
?>

Discussion

The FilterIterator encloses a DirectoryIterator and only allows certain elements to emerge. It's up to the accept( ) method to return true or false to indicate whether a particular element (accessed with $this->current( )) is OK. In Figure, accept( ) uses a regular expression to make that determination, but your code can use any logic you like.

If your pattern can be expressed as a simple shell "glob" (e.g. *.*), use the glob( ) function to get the matching filenames. Figure finds all the text files in a particular directory.

Using glob( )

<?php
foreach (glob('/usr/local/docs/*.txt') as $file) {
   $contents = file_get_contents($file);
   print "$file contains $contents\n";
}
?>

The glob( ) function returns an array of matching full pathnames. If no files match the pattern, glob( ) returns false.

See Also

Recipe 24.9 details iterating through each file in a directory recursively; documentation on FilterIterator at http://www.php.net/~helly/php/ext/spl/classFilterIterator.html and on glob( ) at http://www.php.net/glob; information about shell pattern matching is available at http://www.gnu.org/software/bash/manual/bashref.html#SEC35.



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