PHP incremental file names - php

Question

I have this function that checks for a filename. If it exists, it increments it by one following this patter:
image.jpg
image1.jpg
image2.jpg
The problem comes on the 4th image, it comes back with 0.jpg.
Here is the relevant code:
...
$filetarget = $this->make_image_filename($directory, $new_filename, $extension);
if(!move_uploaded_file($file['tmp_name'], $filetarget)){
$error[$index] = 'copy';
}
...
private function make_image_filename($directory, $name = '', $extension){
if(empty($name)) $name = 'NULL';
$filetarget = $directory.$name.$extension;
if(file_exists($filetarget)){
$name = $this->increment_filename($name);
return $this->make_image_filename($directory, $name, $extension);
} else {
return $filetarget;
}
}
private function increment_filename($name){
$index = $this->get_filename_index($name);
if(is_numeric($index)){
$pos = strpos($name, $index);
$name = substr($name, 0, $pos);
}
if(is_null($index)){
$index = 0;
}
++$index;
return $name.$index;
}
private function get_filename_index($name){
// CHECK FOR INDEX
$i = 1;
$index = substr($name, -$i);
$last_chars = substr($name, -$i);
while(is_numeric($last_chars)){
++$i;
$last_chars = substr($name, -$i);
if(is_numeric($last_chars)){
$index = $last_chars;
}
}
if(is_numeric($index)){
return $index;
} else {
return NULL;
}
}
I am in the process now of isolating this code on my local server to run some tests. Can you see anything inherently flawed in this process?

Answer 1

Here is a function I use to do the same thing:
function make_unique($full_path) {
$file_name = basename($full_path);
$directory = dirname($full_path).DIRECTORY_SEPARATOR;
$i = 2;
while (file_exists($directory.$file_name)) {
$parts = explode('.', $file_name);
// Remove any numbers in brackets in the file name
$parts[0] = preg_replace('/\(([0-9]*)\)$/', '', $parts[0]);
$parts[0] .= '('.$i.')';
$new_file_name = implode('.', $parts);
if (!file_exists($new_file_name)) {
$file_name = $new_file_name;
}
$i++;
}
return $directory.$file_name;
}
(except it make file names like image(1).jpg image(2).jpg)

Answer 2

How about this:
function get_next_file_name($file) {
if (!preg_match('/^(\D+)(\d*)(\.\S+)$/', $file, $match)) {
throw new Exception('bad file name format');
}
return $match[1] . (empty($match[2]) ? 1 : ($match[2] + 1)) . $match[3];
}
echo get_next_file_name('image.jpg'), "\n"; // prints image1.jpg
echo get_next_file_name('image1.jpg'), "\n"; // prints image2.jpg
echo get_next_file_name('image999.jpg'), "\n"; // prints image1000.jpg