powershell - How do I parse a date in PowerShell?

Question

I write a script that removes backups older than five days. I check it by the name of the directory and not the actual date.

How do parse the directory name to a date to compare them?

Part of my script:

...

foreach ($myDir in $myDirs)
{
  $dirName=[datetime]::Parse($myDir.Name)
  $dirName= '{0:dd-MM-yyyy}' -f $dirName
  if ($dirName -le "$myDate")
  {
        remove-item $myPath\$dirName -recurse
  }
}
...

Maybe I do something wrong, because it still does not remove last month's directories.

The whole script with Akim's suggestions is below:

Function RemoveOldBackup([string]$myPath)
{

  $myDirs = Get-ChildItem $myPath

  if (Test-Path $myPath)
  {
    foreach ($myDir in $myDirs)
    {
      #variable for directory date
      [datetime]$dirDate = New-Object DateTime

      #check that directory name could be parsed to DateTime
      if([datetime]::TryParse($myDir.Name, [ref]$dirDate))
      {
            #check that directory is 5 or more day old
            if (([DateTime]::Today - $dirDate).TotalDays -ge 5)
            {
                  remove-item $myPath\$myDir -recurse
            }
      }
    }
  }
  Else
  {
    Write-Host "Directory $myPath does not exist!"
  }
}

RemoveOldBackup("E:\test")

Directories names are, for example, 09-07-2012, 08-07-2012, ..., 30-06-2012, and 29-06-2012.

Answer 1

[DateTime]::Today尝试计算解析目录名和解析结果的区别：

foreach ($myDir in $myDirs)
{
    # Variable for directory date
    [datetime]$dirDate = New-Object DateTime

    # Check that directory name could be parsed to DateTime
    if ([DateTime]::TryParseExact($myDir.Name, "dd-MM-yyyy",
                                  [System.Globalization.CultureInfo]::InvariantCulture,
                                  [System.Globalization.DateTimeStyles]::None,
                                  [ref]$dirDate))
    {
        # Check that directory is 5 or more day old
        if (([DateTime]::Today - $dirDate).TotalDays -ge 5)
        {
            remove-item $myPath\$dirName -recurse
        }
    }
}