Powershell Regex date conversion - regex

Question

any idea why the following isnt working?
.................................................................................................................................................................................................................................................................................
$files = #'
name 14122012 text.doc
things 08092003.docx
hi v03.03 text 05062007 file.txt
hello world 31052006.ppt
names v04 12122012.xml
sdsf 29082013 dsf.php
'# -split '\n'
foreach ($File in $files) {
$file -match '(0[1-9]|[12][0-9]|3[01])(0[1-9]|1[012])(19|20)[0-9]{2}' | Out-Null
$File -replace "$(($matches).values)" , "$(get-date "$(($matches).Values)" -Format yyyyddMM)"
}
powershell output error is, for some reason its trying to add "20 12 14" to the string for conversion :S
Get-Date : Cannot bind parameter 'Date'. Cannot convert value "20 12 14 14122012" to type "System.DateTime". Error: "String was not recognized as a valid DateTime."
At line:13 char:9
+ get-date <<<< "$(($matches).Values)" -Format yyyyddMM
+ CategoryInfo : InvalidArgument: (:) [Get-Date], ParameterBindingException
+ FullyQualifiedErrorId : CannotConvertArgumentNoMessage,Microsoft.PowerShell.Commands.GetDateCommand
and
$files = #'
11.12.2012
11.12.12
15 12 2013
5 06 2013
'# -split '\n'
foreach ($File in $files) {
$file -match '\d{2}\.\d{2}\.\d{2,4}' | Out-Null
$file -match '(0[1-9]|[12]\d|3[01])\s\d{2}\s\d{2,4}'| Out-Null
$File -replace "$(($matches).values)" , "$(get-date "$(($matches).Values)" -Format yyyyMMdd)"
}
15 12 2013
Get-Date : Cannot bind parameter 'Date'. Cannot convert value "15 15 12 2013" to type "System.DateTime". Error: "String was not recognized as a valid DateTime."
At line:13 char:9
+ get-date <<<< "$(($matches).Values)" -Format yyyyMMdd
+ CategoryInfo : InvalidArgument: (:) [Get-Date], ParameterBindingException
+ FullyQualifiedErrorId : CannotConvertArgumentNoMessage,Microsoft.PowerShell.Commands.GetDateCommand
5 06 2013
Get-Date : Cannot bind parameter 'Date'. Cannot convert value "15 15 12 2013" to type "System.DateTime". Error: "String was not recognized as a valid DateTime."
At line:13 char:9
+ get-date <<<< "$(($matches).Values)" -Format yyyyMMdd
+ CategoryInfo : InvalidArgument: (:) [Get-Date], ParameterBindingException
+ FullyQualifiedErrorId : CannotConvertArgumentNoMessage,Microsoft.PowerShell.Commands.GetDateCommand

Answer 1

It's doing what it's supposed to do. $matches is a hash table of the the base capture (0) and each capture group:
$text = 'name 14122012 text.doc'
$regex = $file -match '(0[1-9]|[12][0-9]|3[01])(0[1-9]|1[012])(19|20)[0-9]{2}' | Out-Null
$matches
Name Value
---- -----
3 2013
2 08
1 29
0 29082013
When you ouput the collection of values as a string, it's going to space separate them:
"$(($matches).values)"
2013 08 29 29082013
That's the normal behaviour for any collection that's converted to a string. You can change the separator character from the default space by changing the Output Field Separator ($OFS)
$OFS = ';'
"$(($matches).values)"
2013;08;29;29082013
That being said, you really don't need to jump through the datetime conversion hoops. You have all the data you need already:
$files = #'
name 14122012 text.doc
things 08092003.docx
hi v03.03 text 05062007 file.txt
hello world 31052006.ppt
names v04 12122012.xml
sdsf 29082013 dsf.php
'# -split '\n'
foreach ($File in $files) {
$file -match '(0[1-9]|[12][0-9]|3[01])(0[1-9]|1[012])((?:19|20)[0-9]{2})' | Out-Null
$File -replace "$($matches[0])" , ($matches[3,2,1] -join '')
}
name 20121214 text.doc
things 20030908.docx
hi v03.03 text 20070605 file.txt
hello world 20060531.ppt
names v04 20121212.xml
sdsf 20130829 dsf.php
It just took a minor re-factoring of the regex to capture all of the year digits, then arrange the captures in the right order and join them together.

Answer 2

Your first problem is that you weren't capturing the entire year (only the first 2 digits), so you need to move the group capture bracket:
$file -match '(0[1-9]|[12][0-9]|3[01])(0[1-9]|1[012])(19|20[0-9]{2})'
Also, $matches returns an array that contains the entire matched string in the first element, followed by an element for each captured group.
For example:
"name 14122012 text.doc" -match '(0[1-9]|[12][0-9]|3[01])(0[1-9]|1[012])(19|20[0-9]{2})'
$matches
Name Value
---- -----
3 2012
2 12
1 14
0 14122012
So you have to recombine the string in a format the get-date will like. In my locale, it would look like this:
$matches[2,1,3] -join " "
12 14 2012
If your locale needs the day of month first, then:
$matches[1..3] -join " "
14 12 2012
which then gives:
$File -replace "$($matches[0])" , "$(get-date $($matches[2,1,3] -join ' ') -Format yyyyddMM)"
for your second line.