Powershell compare months and exclude which are not required - powershell

Question

I have a text file as shown below. I need to preserve the files which are within 6 months old (from the previous month) and write every other content to other file which are more than 6 months old.
What I've done so far is like:
$array3 =
do {
foreach($monthl in $monthlookup)
{
$mnthl = $monthl -split '-'
$m_day = $mnthl[1]
$m_month = $mnthl[2]
$m_year = $mnthl[3]
$m_temp = 0
$prevmonth = (Get-Date).AddMonths(-1).ToString("dd-MM-yy")
while(($m_temp -eq "0"))
{
if(($m_month -ge $startmonth) -and ($m_month -le $prevmonth))
{
$monthl | Add-Content "C:\each_month_latest.txt"
break;
}else
{
$monthl | Add-Content "C:\exclusions.txt"
}
}
}
} until ($m_month -ge $m)
What the issue I identified here is like: If the current month is 1, then it wont go back to the last 6 months and check, as I use just strings here.
Any suggestions or code improvements, anyone of you can think of..? Would be really appreciated.
Edit
monthlookup will look like:
testdatabase-30-11-14-23-00
testdatabase-31-12-14-23-00
testdatabase-30-01-15-23-00
testdatabase-31-01-15-23-00
testdatabase-27-05-15-23-00
testdatabase-28-02-15-23-00
testdatabase-31-03-15-23-00
testdatabase-30-04-15-23-00
testdatabase-31-05-15-23-00
$m is $m = Get-Date -Format "MM"

Answer 1

Well, I don't completly understand what you want to do but here some tipps:
$prevmonth = (Get-Date).AddMonths(-1).ToString("dd-MM-yy") shouldn't be done each time within the foreach loop
You could extract the date using a simple regex: [regex]::Match('testdatabase-30-11-14-23-00', '^.*?-(\d{2}-\d{2}-\d{2}-\d{2}-\d{2}$)').Groups[1].Value
Parse the date using [datetime]::ParseExact and a format string
So it could look like this:
# this doesn't have to be done each time in the foreach loop
$sixMonthBefore = (Get-Date).AddMonths(-6)
foreach($monthl in $monthlookup)
{
# extract the date
$dateString = [regex]::Match($monthl, '^.*?-(\d{2}-\d{2}-\d{2}-\d{2}-\d{2}$)').Groups[1].Value
# create a datetime using format string
$date = [datetime]::ParseExact($dateString, 'dd-MM-yy-HH-mm', $null)
if ($date.Month -eq (Get-Date).Month -and $date.Year -eq (Get-Date).Year)
{
Write-Host "$monthl is from this month"
}
elseif ($date -gt $sixMonthBefore)
{
$monthl | Add-Content "C:\each_month_latest.txt"
}
else
{
$monthl | Add-Content "C:\exclusions.txt"
}
}