PowerShell and CSV files - powershell

Question

I have a script, that runs with a for loop.
It outputs 3 variables: $A, $B and $C.
I would like at each iteration to outout those 3 variables onto the same line inside a file, instead of the standard output (each of them separaed by a comma).
I would like to add a header. I am cerating a CSV file.
I have seen several way to output variable inside a CSV file, but not inside a for loop.
Any way to concatenate those 3 variables and append them to a file?
Write-Host $A ',' $B ',' $C | Out-File -FilePath C:\temp\TEST.csv -Append

Answer 1

$A = 'foo'
$B = 'bar'
$C = 'baz'
"$A,$B,$C" # outputs Foo,Bar,Baz
However, if you're working with CSVs, the preferred method is to use Import-Csv and Export-Csv, which handles the formatting for you.

Answer 2

Write-Host output goes directly to the host console. It cannot be pipelined. Also, as has already been mentioned, you normally want to use the Import-Csv and Export-Csv cmdlets when dealing with CSVs (particularly since you want a CSV with headers).
To get a bunch of variables in a form that is exportable by Export-Csv construct a custom object like this:
New-Object -Type PSObject -Property #{
'X' = $A
'Y' = $B
'Z' = $C
} | Export-Csv 'C:\Temp\test.csv' -NoType
The keys of the property hashtable become the column titles of the CSV.
Since you say you want to export data from a for loop you'll need to add the parameter -Append to Export-Csv:
for (...) {
New-Object ... | Export-Csv 'C:\Temp\test.csv' -NoType -Append
}
That is because for loops don't write to the pipeline, meaning that something like this won't work:
for (...) {
New-Object ...
} | Export-Csv 'C:\Temp\test.csv' -NoType
However, depending on what your actual loop looks like you might be able to substitute it with a combination of the range operator (..) and a ForEach-Object loop:
1..5 | ForEach-Object {
New-Object ...
} | Export-Csv 'C:\Temp\test.csv' -NoType

Answer 3

Provided at each iteration to outout those 3 variables is not meant literal,
you could gather the for loops output in a variable via a PSCustomObject and then Export-Csv the result.
For demonstration a simple counting loop:
$Result = for ($i=1;$i -lt 5;$i++){[pscustomobject]#{X=$i;Y=$i+1;Z=$i+2}}
$Result
X Y Z
- - -
1 2 3
2 3 4
3 4 5
4 5 6
Then Export/ConvertTo-Csv:
$Result|ConvertTo-Csv -NoTypeInformation
"X","Y","Z"
"1","2","3"
"2","3","4"
"3","4","5"
"4","5","6"