How can I change a file’s extension using PHP?

How can I change a file’s extension using PHP?

Ex: photo.jpg to photo.exe

Answer

In modern operating systems, filenames very well might contain periods long before the file extension, for instance:

my.file.name.jpg

PHP provides a way to find the filename without the extension that takes this into account, then just add the new extension:

function replace_extension($filename, $new_extension) {
    $info = pathinfo($filename);
    return $info['filename'] . '.' . $new_extension;
}