Regex and Various Matches

PowerShell Help
1

I am retrieving a single string stored in a text file in a format matching below, and then find all files matching the string in a specified directory.

String possibilities in file (n = any number):
17-0201n
17-0201-cnn
17-0201M_n
17-0201M-cn_n
17-0201E-cn_n

17-0201… is just an example. It could also be 15-0923, 19-1215M, and so on.

17-0201 should match only 17-0201, not 17-0201M or 17-0201E.

I’m assuming using a regex would be best to match files to the string in the file, so that is where I am stuck. If not, kindly direct me to a better solution.

Thanks for your input.

2

Is this what you are looking for?

$values = "17-0201_n",
          "17-0201-cn_n",
          "17-0201M_n",
          "17-0201M-cn_n",
          "17-0201E-cn_n",
          "15-0923",
          "19-1215M"


$matched = foreach ($value in $values) {
    Write-Host ("Found match {0} for value {1}" -f [regex]::Match($value, "\d{2}-\d{4}").groups[0].Value, $value)
    [regex]::Match($value, "\d{2}-\d{4}").groups[0].Value
}

$matched | Select -Unique

Output:

Found match 17-0201 for value 17-0201_n
Found match 17-0201 for value 17-0201-cn_n
Found match 17-0201 for value 17-0201M_n
Found match 17-0201 for value 17-0201M-cn_n
Found match 17-0201 for value 17-0201E-cn_n
Found match 15-0923 for value 15-0923
Found match 19-1215 for value 19-1215M

17-0201
15-0923
19-1215

You could update the pattern to “^\d{2}-\d{4}$” if you only expect a match for 15-0923

3

“You could update the pattern to “^\d{2}-\d{4}$” if you only expect a match for 15-0923”

Thanks, Rob. Your example accomplishes part of what I need, which I already have something similar working. My problem is that I am trying to account for an additional character after the last 4 digits which may or may not exist, and same with “-cn”.

Examples: 17-0201, 17-0201-cn, 17-0201M-cn, and so on.

So, take:

[string] = '17-0201'

Then use a regex to see if any file name(s) in folder X matching the string.

This should return matching files:

17-0201_0
17-0201-cn_0
17-0201-cn_1
17-0201-cn_2

(the _0, _1, etc. is used in the file name to prevent original files from being overwritten)

But not return:
17-0201M_0
17-0201M-cn_0
17-0201E-cn_0

Hope this makes more sense.

Thanks again.

4

You’ll need to define the character(s) after the string that either should or should not be there to be considered a match. For instance are “-” or “_” the only characters that can be there and be considered a match on the base pattern. Or, could it be any non letter (or number). What about white space? Etc.

5 
$string = '17-0201_n
 17-0201_0
17-0201-cn_0
17-0201M_0
17-0201M-cn_0
 17-0201
 17-0201 spacehere
 17-0201-BE
 17-0201_1' -split "`n"

# Match 2 numbers, dash, and 4 numbers ONLY -OR-
# Match Non word character plus underscore                                                        
foreach ($s in $string){
    [regex]::Matches($s,'\d{2}-\d{4}$|\d{2}-\d{4}[\W_].*').value
}
# Results:
# 17-0201_n
# 17-0201_0
# 17-0201-cn_0
# 17-0201
# 17-0201 spacehere
# 17-0201-BE
# 17-0201_1
6

Thanks everyone for the input.

Shortly after my last response, I did come up with the (simple) solution I needed but haven’t been able to follow up until now. So here is the regex I came up with (for anyone else that might need it down the road):

[string]$TimeCodeEmpty = "(\d{2}-\d{4}$)"
[string]$TimeCodeM = "(\d{2}-\d{4}M$)"
[string]$TimeCodeA = "(\d{2}-\d{4}A$)"
[string]$TimeCodeE = "(\d{2}-\d{4}E$)"
[string]$regex_TimeCode = "$TimeCodeEmpty|$TimeCodeM|$TimeCodeA|$TimeCodeE"

Pretty simple, eh? Sometimes you just need to pull away and not overlook things.

Thanks again!