PowerShell regex to get just hex part in strings

I’m working on a function that gets the map of string key and it’s hex value. I got the string key part working, but I’m having trouble getting the hex part to work. This is my function so far:

function Get-Contents4_h{
  [cmdletbinding()]
  Param ([string]$fileContent) 

          #define Error_Failed_To_Do_A          0x81A0  /* random comments */
          #define Error_Failed_To_Do_B      0x810A

  # create an ordered hashtable to store the results
  $errorMap = [ordered]@{}
  # process the lines one-by-one
  switch -Regex ($fileContent -split '\r?\n') {
      'define ([\w]*)' { # Error_Failed_To_Do_  #this works fine
          $key = ($matches[1]).Trim()
      }
      '([0x\w]*)' {  # 0x04A etc #this does not work
          $errorMap[$key] = ($matches[1]).Trim()
      }
  }
  # output the completed data as object
  #[PsCustomObject]$errorMap
  return $errorMap
}

I’m going to be looping through the returned map and matching the hex value with the key in another object.

This is what the string parameter to the function looks like:

#define Error_Failed_To_Do_A            0x81A0  /* random comments */
#define Error_Failed_To_Do_B        0x810A

For some reason my

0x\w

regex is not returning anything in regex101.com. I’ve had luck with that with other hex numbers but not this time.

I’ve tried this and other variations as well: ^[\s\S]*?#[\w]*[\s\S]+([0x\w]*)

This is with powershell 5.1 and VS Code.

>Solution :

You need to remove the [...] range construct around 0x\w – the 0x occurs exactly once in the input string, and the following characters appears at least once – but the expression [0x\w]* could be satisfied by an empty string (thanks to the *, 0-or-more quantifier).

I’d suggest matching the whole line at once with a single pattern instead:

switch -Regex ($fileContent -split '\r?\n') {
    '^\s*#define\s+(\w+)\s+(0x\w+)' {
        $key,$value = $Matches[1,2] |ForEach-Object Trim          
        $errorMap[$key] = $value
    }
}