Parse and replace multiple variants using PowerShells regex

Question

Parsing a text document using the code below matches every instance of '333', however I would like only the three examples below to be changed.

(Get-Content input.json) | ForEach-Object {
    $_ -replace '333', '666'
} | Set-Content output.json

This should change:

• "se333" → "se666"
• "SE333" → "SE666"
• "333" → "666"

This should be left unchanged:

• "1212333" → unchanged
• "3331212" → unchanged
• "333asda" → unchanged
• "asd333" → unchanged

What is the PowerShell regex solution for this?

Answer 1

You may use

(?i)(?<=\b(?:se)?)333\b

See the regex demo

Details

• (?i) - case insensitive modifier
• (?<=\b(?:se)?) - before 333 there must be a word boundary and anoptional substrin se
• 333 - a literal substring
• \b - a trailing word boundary.

Powershell test:

PS> $s = "se333 SE333 333 1212333 3331212 333asda asd333"
PS> $s -replace '(?i)(?<=\b(?:se)?)333\b', '666'
se666 SE666 666 1212333 3331212 333asda asd333