Search and replace all spaces between quotes with uderscore

Question

Hello,
I'm new on Powershell and I'm trying to make the script that:
searches over file and replaces all the spaces which have been found between quotes;
removes all quotes (except these which has not value eg "").
For example:
Source file:
string3=string4 string="string1 string2 string23" string8="" string5="string7 string8"
Destination file:
string3=string4 string=string1_string2_string23 string8="" string5=string7_string8
I have been created script that searches the data correctly
$file="c:\scripts\mk.txt"
$data=Get-Content $file
$1
$regex = [regex]@'
(?x) # ignore pattern whitespace option
(?<test>(["'])(?:(?=(\\?))\2.)*?\1)
$data |% {
if ($_ -match $regex){
new-object psobject -property @{
test = $matches['test']
}#when adding "|select-object test" I'm getting the correct data
I have stopped here on search / replace operation (from space to underscore, and by removing the quotes leaving the empty quotes non touched). Can you help me to finish the script?
Thanks!

Answer 1

Try this.  It uses the [Regex] Replace static method, with a script block delegate:
$file="c:\scripts\mk.txt"
$data=Get-Content $file
$regex = '(\S+=[^"\s]+)|(\S+="[^"]+")'
$delegate = { $args[0].value.replace(' ','_') -replace '"(.+)"','$1' }
$data |% { [regex]::Replace($_,$regex,$delegate) }
[string](0..33|%{[char][int](46+("686552495351636652556262185355647068516270555358646562655775 0645570").substring(($_*2),2))})-replace " "