How to manage transition from one year to another in powershell - powershell

Question

I've this list of directories to ZIP :
2019_40
2019_41
2019_42
2019_43
2019_44
2019_45
2019_46
2019_47
2019_48
2019_49
2019_50
2019_51
2019_52
2020_01
2020_02
2020_03
2020_04
2020_05
Here my code to zip them. I set the year 2020 for simulation what will happen the next year :
### Set 7Zip excutabe as variable
$7Zip = gci c:\Program* -include '7z.exe' -recurse -ea 4|select -first 1 -expand fullname
# Date
$Year = get-date -UFormat %Y
$WeekNb = get-date -UFormat %V
#Simulation the future
$Year = "2020"
$WeekNb = "02"
$Dir_To_Zip = Get-ChildItem -path "C:\Temp\LOG Script"
Foreach ($element in $Dir_To_Zip )
{
$DirName = $element.Name
$DirNameY = $DirName.Substring(0, $DirName.Length -3 )
$DirNameW = $DirName.Substring($DirName.Length -2)
if ( $DirNameW -lt $WeekNb - 4 )
{
& $7zip a "$element.zip" "$element" }
}
In this state my script is ziping the directories of the year 2020 only, not the 2019.
If I change this line :
if ( $DirNameW -lt $WeekNb - 4 )
by this one
if (( $DirNameY -le $Year -1 ) -or ($DirNameW -lt $WeekNb -4 ))
All directories are zipped

Answer 1

With the -or condition, the $DirNameY was not considered like a string number so I corrected like this :
#Set 7Zip excutabe as variable
$7Zip = gci c:\Program* -include '7z.exe' -recurse -ea 4|select -first 1 -expand fullname
# Date
$Year = get-date -UFormat %Y
$WeekNb = get-date -UFormat %V
# DEBUG pour forcer l annee et le numero de seamine
$Year = "2020"
$WeekNb = "05"
# List files to  Zip
$Dir_To_Zip = Get-ChildItem -path "C:\Temp\LOG Script"
Foreach ($element in $Dir_To_Zip )
{
$DirName = $element.Name
$DirNameY = $DirName.Substring(0, $DirName.Length -3 )
$DirNameW = $DirName.Substring($DirName.Length -2)
$DirNameW = $DirNameW.trimstart('0')
if (( $DirNameY -lt $Year -1 ) -or ($DirNameW -lt $WeekNb -4 ))
{
& $7zip a "$element.zip" "$element" }
}