Question regarding incrementing a string value in a text file using Powershell - powershell

Question

Just beginning with Powershell. I have a text file that contains the string "CloseYear/2019" and looking for a way to increment the "2019" to "2020". Any advice would be appreciated. Thank you.

Answer 1

If the question is how to update text within a file, you can do the following, which will replace specified text with more specified text. The file (t.txt) is read with Get-Content, the targeted text is updated with the String class Replace method, and the file is rewritten using Set-Content.
(Get-Content t.txt).Replace('CloseYear/2019','CloseYear/2020') | Set-Content t.txt
Additional Considerations:
General incrementing would require a object type that supports incrementing. You can isolate the numeric data using -split, increment it, and create a new, joined string. This solution assumes working with 32-bit integers but can be updated to other numeric types.
$str = 'CloseYear/2019'
-join ($str -split "(\d+)" | Foreach-Object {
if ($_ -as [int]) {
[int]$_ + 1
}
else {
$_
}
})
Putting it all together, the following would result in incrementing all complete numbers (123 as opposed to 1 and 2 and 3 individually) in a text file. Again, this can be tailored to target more specific numbers.
$contents = Get-Content t.txt -Raw # Raw to prevent an array output
-join ($contents -split "(\d+)" | Foreach-Object {
if ($_ -as [int]) {
[int]$_ + 1
}
else {
$_
}
}) | Set-Content t.txt
Explanation:
-split uses regex matching to split on the matched result resulting in an array. By default, -split removes the matched text. Creating a capture group using (), ensures the matched text displays as is and is not removed. \d+ is a regex mechanism matching a digit (\d) one or more (+) successive times.
Using the -as operator, we can test that each item in the split array can be cast to [int]. If successful, the if statement will evaluate to true, the text will be cast to [int], and the integer will be incremented by 1. If the -as operator is not successful, the pipeline object will remain as a string and just be output.
The -join operator just joins the resulting array (from the Foreach-Object) into a single string.

Answer 2

AdminOfThings' answer is very detailed and the correct answer.
I wanted to provide another answer for options.
Depending on what your end goal is, you might need to convert the date to a datetime object for future use.
Example:
$yearString = 'CloseYear/2019'
#convert to datetime
[datetime]$dateConvert = [datetime]::new((($yearString -split "/")[-1]),1,1)
#add year
$yearAdded = $dateConvert.AddYears(1)
#if you want to display "CloseYear" with the new date and write-host
$out = "CloseYear/{0}" -f $yearAdded.Year
Write-Host $out
This approach would allow you to use $dateConvert and $yearAdded as a datetime allowing you to accurately manipulate dates and cultures, for example.