how to put 0s in front of single digit numbers

Question

I am currently transferring music to an mp3 player that organizes numbers differently than, say, an ipod. I need to put 0s in front of the single digit numbers (e.g. 1 needs to be 01, 2 needs to be 02) because if there is not a 0 in front of a single digit number and the track list includes a number of songs greater than ten, the order is as follows for an album with, say, 13 songs: 1,11,12,13,2,3,4,5,6,7,8,9. Is there a powershell command that I can use to easily put 0s in front of single digit numbers without having to manually put them in? And/or is there a way to simply add a numbered list to song files in a folder while maintaining the same order? Or lastly can I just make it so that instead of organizing numbers like 1,11,12, etc.. the program changes its order pattern to 1,2,3,4,5,6,7,8,9,10,11,12, etc. i.e. without putting 0s in front of single digit numbers?

Thank you.

Answer 1

let's first build a MWE to recreate your scenario:

mkdir tmp
cd tmp
FOR /L %i IN (1,1,22) DO echo nothing > my-%i-music-file.mp3

this creates a directory with some fake files with number in their names

you issue is that rather than a numeric sort, you're getting an alphabetical sort and therefore you may work around it by padding zeroes, which you can achieve with the following command:

FOR /L %i IN (1,1,9) DO move my-%i-music-file.mp3 my-0%i-music-file.mp3

of course this addressed the specific scenario I just built, because you did not provide further details on yours so this addresses from 1 to 9 to become 01 to 09 but the same goes for any amount of zeros you might need to prepend

Answer 2

Your player is sorting alphabetical, probably because the sort is done on filename which contains both numbers and letters. This is why mp3s++ usually have a Track ID/Number attribute embedded, which is just a number and can be used for numeric sort. If and how you can make your program sort using the track number attribute (if there is one), depends on the program.

Demo of the problem and how to use numeric sorting in PowerShell:

#Sort by filenames -> alphabetical order = problem
"1_ThisSong.mp3", "2_YourSong.mp3","12_MySong-mp3" | Sort-Object
1_ThisSong.mp3
12_MySong-mp3
2_YourSong.mp3

#Extract the number before _, cast to int-type and sort -> Numeri sort is possible
"1_ThisSong.mp3", "2_YourSong.mp3","12_MySong-mp3" | Sort-Object { $_.Split("_")[0] -as [int] }
1_ThisSong.mp3
2_YourSong.mp3
12_MySong-mp3

To display numbers using two digits in PowerShell, you can use string-format. Ex:

1..13 | ForEach-Object { "{0:00} - MyNewFilename" -f $_ }

01 - MyNewFilename
02 - MyNewFilename
03 - MyNewFilename
04 - MyNewFilename
05 - MyNewFilename
06 - MyNewFilename
07 - MyNewFilename
08 - MyNewFilename
09 - MyNewFilename
10 - MyNewFilename
11 - MyNewFilename
12 - MyNewFilename
13 - MyNewFilename

Demo to rename files so numbers use two digits:

(Get-ChildItem).Name
12_MySong.mp3
1_ThisSong.mp3
2_YourSong1.mp3

Get-ChildItem -Path 'D:\New folder' -Filter "*.mp3" | ForEach-Object {
    $matcheval = {
        param($match)

        #Output number-value as two digits
        "{0:00}" -f ($match.Value -as [int])
    }

    #Replace any number use two-digit-format
    $BaseName = [regex]::Replace($_.BaseName,"\d+",$matcheval)

    #Rename file with updated basename
    Rename-Item -Path $_.FullName -NewName "$BaseName$($_.Extension)"

}

(Get-ChildItem).Name
01_ThisSong.mp3
02_YourSong01.mp3
12_MySong.mp3