How to identify in the directory the file with higher numbering and save in a variable?

I have in a folder named files sequentially

file1
file2
file3

I know glob or scandir can list the files in a directory, but how would it be possible to identify the most current file (numbering) to sequence and save the next files with correct numbering?

summarizing: how to identify with PHP the file with higher number and save this in a variable?

Solution

You can get the newest file from the directory.
Remove 'file' substring from the file name, to get the last file number
Increment the number and do string operations to get your new filename.

Try the following:

// $directory_path is the directory you are scanning
// Scan directory in descending order
$files = scandir($directory_path, SCANDIR_SORT_DESCENDING);
$last_file = $files[0];

// extract the last file number
$last_file_no = (int)str_replace('file', '', $last_file);

// prepare the new file name
$new_file_no = $last_file_no + 1;
$new_file_name = 'file'. $new_file_no;