windows - How to remove comments from text file -

my text file contains 1 line comments being "// ". 2 forward slashes , space. these may either take whole line or last part of line. each comment not extend beyond line it's on. no /* */ type comments crossing multiple lines.

in simple terms, comments start "//space" anywhere on line. starting "//space" should removed , trailing spaces on line should removed. leading spaces should stay. blank lines should removed.

sample file:

// comment x = 1 // comment after double slash x = 2  x = 3  // above blank line           // comment on record nothing precedes it, should deleted.    y = 4 // line leading spaces should kept. z = "//path"; // first double slashes not comment since space missing after "//" // last comment line. 

result file (no trailing spaces, keep leading spaces.:

x = 1 x = 2 x = 3    y = 4 z = "//path"; 

i can remove blank lines using gc file.txt | where-object { $_ -ne ''} > result.txt. i'm having trouble reading beginning part of line "//" comment part.

i tried findstr haven't found how read each line "//" , trim spaces out.

i write script program loop throught file , this, seems there should way accomplish using simple 1 or 2 line powershell or bat file command.

what easiest way (shortest amount of code) remove these comments while keeping uncommented contents of file?

since seem equate "easy" "short", here's simple solution:

gc .\samplefile.txt|%{$_-replace"(.*)(// .*)",'$1'}|?{$_} 

if it's important :-)

a bit more verbose version (still using regex):

get-content .\samplefile.txt | where-object {     -not ([string]::isnullorempty($_.trim()) -or $_-match"^\s*// ") } |foreach-object { $_ -replace "(.*)(// .*)",'$1' } 

---

that being said, (personally) go more verbose , easier-to-read/maintain solution:

to remove after //, easiest way find first occurrence of // string.indexof() , grab first part string.substring():

ps c:\> $commentedstring = "content // comment" ps c:\> $commentindex    = $commentedstring.indexof('// ') ps c:\> $commentedstring.substring(0,$commentindex) content  

for indented comments can use string.trim() remove whitespace beginning , end of string:

ps c:\> "    // indented comment" -match '^//' true 

you can use foreach-object cmdlet go through every line , apply above:

function remove-comments {     param(         [string]$path,         [string]$outfile     )      # read file, remove comments , blank lines     $cleanlines = get-content $path |foreach-object {          $line = $_          # trim() removes whitespace both ends of string         $trimmedline = $line.trim()          # check if what's left either nothing or comment         if([string]::isnullorempty($trimmedline) -or $trimmedline -match "^// ") {             # if so, return nothing (inside foreach-object "return" acts "coninue")             return          }          # see if non-empty line contains comment         $commentindex = $line.indexof("// ")          if($commentindex -ge 0) {             # if so, remove comment             $line = $line.substring(0,$commentindex)         }          # return $line $cleanlines         return $line     }      if($outfile -and (test-path $outfile)){         [system.io.file]::writealllines($outfile, $cleanlines)     } else {         # no outfile specified, write lines pipeline         write-output $cleanlines     } } 

applied sample:

ps c:\> remove-comments d:\samplefile.txt x = 1 x = 2 x = 3