Name each new dir with the next available number with php - php

Question

I'm working on a php file where I want to create one or more directories with names ranging from 1 to 999 or more. I'm creating the first of all directories using the following code:
<?php
$id = '001';
mkdir($id)
?>
What I want to succeed is to automatically create a new directory using as a name the next available number (i.e. 002, 003, 004, 005 etc) either as a string or an integer. However, I really stuck and I try to use:
<?php
$id = 001;
if (file_exists($id)) {
$id = $id + 1;
mkdir($id);
}
?>
..but it doesn't work. Any ideas?
I forgot to mention that the above code is part of the if statement inside the same php code.

Answer 1

Several ways to do this, depending on your use case. This function may work for you:
<?PHP
function makedir($id){
if(file_exists($id)){
$id++;
makedir($id);
}else{
mkdir($id);
return true;
}
}
makedir(1);
This solution of incremented directory names is going to become ugly after a while though; you should probably find a better solution to your problem.

Answer 2

You could do something like this:
// Loop through all numbers.
for ($i = 1; $i <= 999; $i++) {
// Get the formatted dir name (prepending 0s)
$dir = sprintf('%03d', $i);
// If the dir doesn't exist, create it.
if (!file_exists($dir)) {
mkdir($dir);
}
}
Edit: the above was assuming you wanted to make all 999 directories. You could do the following to just append the next available number:
function createDir($dir) {
$newDir = $dir;
$num = 1;
while (file_exists($newDir)) {
$newDir = $dir.sprintf('%03d', $num++);
}
return $newDir;
}