Powershell - odd line feed behaviour

Question

I'n new to Powershell so apologies if this is an obvious question. I have the following function which delimits a string:

 [int[]]$rec02 = 3,2,1,4,3,3,5,5,6,1,19,45,2,3,50

 function delimitString([string]$text, [int[]]$arrDelims)
        {
                [string]$out;
                [int]$total=0;
                foreach($d in $arrDelims)
                {        
                    $out += $text.substring($total,$d)+",";
                    $total +=$d;
                }

                $out += $text.substring($total,$text.length-$total)+",";
                return $out;
        }

When this is called as follows: delimitString "gjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjjlllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllfffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffllllllllll" $rec02

How can I suppress/why are there new line/carriage returns at the start/end of the output?

gjj,jj,j,jjjj,jjj,jjj,jjjjj,jjjjj,jjjjjj,j,jjjjlllllllllllllll,llllllllllllllll lllllllllllllllllllllllllllll,ll,lll,llllllllllllllllllllllllllffffffffffffffff ffffffff,ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff fffffffffffffffffffffffffffffffffffffffffllllllllll,

I eventually write this to a file and therefore I am ending up with blank lines in the output.

filimonic · Accepted Answer · 2014-07-26 05:23:45Z

[string]$out is not initialization. It jost outputs variable named 'out' as an addition to return. As there is not $out variable, before output it creates it with default value (empty string). When outputting this manner, it adds newline at the end of each outputting line.

So, [string]$out is actually (in your case) New-Object -TypeName 'System.String' -ArgumentList @([System.String]::Empty), as you see it is Function that returns an object

The same problem is with New-Item function. It returns new item's object, so, when you use it in function, you should send output to null

    Function TestReturn {
    New-Item -Path $( [System.IO.Path]::GetTempFileName() + '.test' ) -ItemType 'File'
    New-Item -Path $( [System.IO.Path]::GetTempFileName() + '.test' ) -ItemType 'File'
    return "Hello, World"
}
TestReturn

returns

;    Mode                LastWriteTime     Length Name                                                                                                                                             
;----                -------------     ------ ----                                                                                                                                             
;-a---        26.07.2014      9:08          0 tmpD9B4.tmp.test                                                                                                                                 
;-a---        26.07.2014      9:08          0 tmpDA03.tmp.test                                                                                                                                 
;Hello, World

To omit this, you should use New-Item ... | Out-Null or put value into a variable $temp = New-Item ... So the correct form is (scroll right!)

        Function TestReturn {
    New-Item -Path $( [System.IO.Path]::GetTempFileName() + '.test' ) -ItemType 'File' | Out-Null
    New-Item -Path $( [System.IO.Path]::GetTempFileName() + '.test' ) -ItemType 'File' | Out-Null
    return "Hello, World"
}
TestReturn

Because of this you should use $out='' or (it you fan typization) $out=[String]'' instead of [string]$out . Those to lines do VERY different things. You line tries to create and output variable. Line $out='' just initializes it.

To write to a file you should use $somevar | Out-File or OutFile -InputObject form

[int[]]$rec02 = @(3,2,1,4,3,3,5,5,6,1,19,45,2,3,50)

 function delimitString([string]$text, [int[]]$arrDelims)
        {
                $out='';
                $total=0;
                foreach($d in $arrDelims)
                {        
                    $out += $text.substring($total,$d)+",";
                    $total +=$d;
                }

                $out += $text.substring($total,$text.length-$total)+",";
                return $out 
        }
$tempFile = [System.IO.Path]::GetTempFileName()
$somevar = delimitString "gjjj...." $rec02 
Write-Host -ForegroundColor Red -NoNewline "BEGIN"
Write-Host -ForegroundColor Green -NoNewline $somevar
Write-Host -ForegroundColor Red "END"

Write-Host -ForegroundColor Red "Out Length: $($somevar.Length)"
$tempFile = [System.IO.Path]::GetTempFileName()
Write-Host -ForegroundColor Green "TempFile: $($tempFile)"
Out-File -FilePath $tempFile -Encoding 'Ascii' -InputObject $somevar
$somevar = Get-Content -Path $tempFile -Encoding 'Ascii'

NB: Out-File with Encoding 'UTF-8' adds BOM record at the beginning. To avoid this use [System.IO.File]::WriteAllText($path,$data,[System.Text.Encoding]::UTF8)

Naigel · Accepted Answer · 2014-07-25 11:28:05Z

1

I'm not sure I well understood the question, but it seems you are trying to initialize variable this way [string]$out;. In fact you are only printing the $out variable (which you never used before) as a string, so you don't get the result you expect by using this piece of code $out += to add something to a string.

Just try change this [string]$out; to this $out = ""; and you should be able to run your code correctly (now $out is a String).

answered Jul 25, 2014 at 11:28

Naigel

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6 Comments

Sidebp Over a year ago

I have amended the usage example slightly. In essence I call the function with a string and split it in intervals defined in the functions input array. I use the out variable to build up the delimited string - this is being assigned to and the output is correct however the start/end of the output has unexpected carriage return/line feed chars.

Naigel Over a year ago

What you get if you try to save the returned value into a variable, let call it $a, and then you call $a.GetType().fullname? Do you Get System.Object[] or System.String?

Naigel Over a year ago

very strange, if I try to execute it I get a System.Object[]

Sidebp Over a year ago

Is that not the base type?

Naigel Over a year ago

("a").GetType().FullName -> System.String @("a").GetType().FullName -> System.Object[] I get a System.Object[] as output variable from your function, if you get a System.String maybe we are looking at a different piece of code ;)

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