Powershell Source Code Encoding / hidden characters [duplicate] - powershell

Question

I have a script which is using the EXIF data from a JPG file to find the DateTaken value. Once found, place the data in $Year and $Month variables.
$objShell = New-Object -ComObject Shell.Application
$folders = (Get-ChildItem G:\ServerFolders\Photos\UnSorted\ -Directory -Recurse -force).FullName
foreach ($Folder in $folders) {
$objfolder = $objShell.Namespace($folder)
foreach ($file in $objFolder.Items()) {
if ($objfolder.GetDetailsOf($file, 156) -eq ".jpg") {
$yeartaken = ($objFolder.GetDetailsOf($File, 12)).Split("/")[2].Split(" ")[0]
$month = $objFolder.GetDetailsOf($File, 12).Split("/")[1]
$monthname = (Get-Culture).DateTimeFormat.GetMonthName($month)
Write-Host $file.Name
}
}
}
So, if the file has a DateTaken as 06/10/2016, $yeartaken is 2016 and $month is 10
I then to Get-Culture to convert the 10 into October. This doesn't work because it's seeing $month as a string.
Cannot convert argument "month", with value: "‎10", for "GetMonthName" to
type "System.Int32": "Cannot convert value "‎10" to type "System.Int32".
Error: "Input string was not in a correct format.""
At line:1 char:3
+ (Get-Culture).DateTimeFormat.GetMonthName($month)
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : NotSpecified: (:) [], MethodException
+ FullyQualifiedErrorId : MethodArgumentConversionInvalidCastArgument
I've tried to convert it to a Integer value using casting or converting, but for some reason it won't convert.
PS> [int]$Test = $month
Cannot convert value "‎10" to type "System.Int32". Error: "Input string was
not in a correct format."
At line:1 char:1
+ [int]$Test = $month
+ ~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : MetadataError: (:) [], ArgumentTransformationMetadataException
+ FullyQualifiedErrorId : RuntimeException

Answer 1

A better approach to working with dates is to convert the date string to an actual DateTime object, which provides all the information you're looking for:
$culture = [Globalization.CultureInfo]::InvariantCulture
$pattern = 'dd\/MM\/yyyy'
$datestring = $objFolder.GetDetailsOf($File, 12).Split(' ')[0]
$datetaken = [DateTime]::ParseExact($datestring, $pattern, $culture)
$year = $datetaken.Year
$month = $datetaken.Month # month (numeric)
$monthname = $datetaken.ToString('MMMM') # month name
Assuming that the date is followed by a time in the format HH:mm:ss you could extend the code to handle the time as well:
$culture = [Globalization.CultureInfo]::InvariantCulture
$pattern = 'dd\/MM\/yyyy HH:mm:ss'
$datestring = $objFolder.GetDetailsOf($File, 12)
$timestamp = [DateTime]::ParseExact($datestring, $pattern, $culture)
$year = $timestamp.Year
$month = $timestamp.Month # month (numeric)
$monthname = $timestamp.ToString('MMMM') # month name
$hour = $timestamp.Hour
...

Answer 2

The date-and-time string returned by $objFolder.GetDetailsOf($File, 12) contains invisible control characters.
You can strip them as follows, after which your code should work:
# Remove the formatting control characters from the string.
$dateTimeStr = $objFolder.GetDetailsOf($File, 12) -replace '\p{Cf}'
# Note: The date format shown is directly recognized by
# PowerShell's [datetime] casts, which use the invariant culture.
$dateTaken = [datetime] $dateTimeStr
$monthname = (Get-Culture).DateTimeFormat.GetMonthName($dateTaken.Month)
\p{Cf} matches characters in the Format Unicode category, which comprises any character that "affects the layout of text or the operation of text processes, but is not normally rendered."
Specifically, in my test file's metadata I found multiple instances of Unicode control characters U+200E (LEFT-TO-RIGHT MARK) and U+200F (RIGHT-TO-LEFT MARK).
As for why these invisible control characters are present (information from this forum post, courtesy of mclayton):
The characters that you are seeing (along with some others, such as nulls) are embedded in BSTRs to allow the calling function to correctly display the string for any locale. It includes such things as the left to right marker that you saw, so that the calling application knows that the characters must be grouped and displayed left to right.
However, it's not quite clear why an explicit direction marker is needed for the default direction, left-to-right, and why seemingly each date component is preceded by one, and the time component even by two; here's an example of what should just be date string 9/5/2015 11:32 AM, with the invisible control characters visualized as PowerShell (Core) 7+ Unicode escape sequences (via Debug-String):
`u{200e}9/`u{200e}5/`u{200e}2015·`u{200f}`u{200e}11:32·AM
As an aside, on a general note: Ansgar Wiecher's answer shows more robust date-time string parsing techniques.
Self-contained sample:
The following example extracts the "Date Taken" field from file test.jpg located in the current folder and converts it to a [datetime] instance - note the need to use .ParseName() in order to pass an object representing the target file that the .GetDetailsOf() method understands:
[datetime] (
($folder = (New-Object -ComObject Shell.Application).
Namespace($PWD.ProviderPath)).
GetDetailsOf($folder.ParseName('test.jpg'), 12) -replace '\p{Cf}'
)