filling a column with a default value for number of rows in file - excel

Question

For the below code id like to add in a default value, lets call it X in the paycentre column in the final output for every row that contains information - can anyone point me in the right direction?
any help greatly appreciated.
$CompletedFile = "C:\Users\filepath.csv"
$path = "C:\Users\originalfile.xls"
$allstaff = #()
#define path for edited docments
Set-Location -Path $path
#Open the Excel file for Whichever csv.
$excelFile = Get-ChildItem -Filter "*file name*"
$excelFile = $path + $excelFile
$excel = new-object -com Excel.Application -Property #{Visible = $false}
#Open the file
$workbook = $excel.Workbooks.Open($excelFile)
#Activate the first worksheet
$sheet = $workbook.Sheets.Item(1)
[void]$sheet.Cells.Item(1, 1).EntireRow.Delete() # Delete the first row
[void]$sheet.Cells.Item(1, 1).EntireRow.Delete() # Delete the 2 row
[void]$sheet.Cells.Item(1, 1).EntireRow.Delete() # Delete the 3 row
[void]$sheet.Cells.Item(1, 1).EntireRow.Delete() # Delete the 4 row
[void]$sheet.Cells.Item(1, 1).EntireRow.Delete() # Delete the 5 row
$workbook.SaveAs($path + "OGEM.csv",6)
#Close workbook and save changes
$workbook.Close($true)
#Quit Excel
$excel.quit()
[System.Runtime.Interopservices.Marshal]::ReleaseComObject($excel) | Out-Null
Set-Location -Path $path
$ImportFileNoHeader = Get-ChildItem -Filter "*OGEM*" -Recurse
Clear-Content $CompletedFile
Add-Content $CompletedFile "Title,First Name,Surname,Number,DoB,Amount,EmployeeNo,Location,Paycentre"
#Fill with content from the source file, but miss the last total row
Get-Content $ImportFileNoHeader | Select-Object -SkipLast 2 |Add-Content $CompletedFile

Answer 1

If I understand the question correctly, below code should do what you want.
First off however, you should use the Join-Path cmdlet to joint paths instead of doing the string concatenation like in $path + $excelFile to avoid getting paths that are missing backslash characters in between the parts.
Secondly, Get-ChildItem returns an array of DirectoryInfo and/or FileInfo objects, not simply filenames. To have it return only FileInfo objects (not directories) use the -File switch.
$path = $env:USERPROFILE
$excelOut = Join-Path -Path $path -ChildPath 'OGEM.csv'
$completedFile = Join-Path -Path $path -ChildPath 'Completed-OGEM.csv'
$defaultValue = 'X'
$filter = '*.xlsx'
$excelFile = Get-ChildItem -Path $path -Filter $filter -File | Select-Object -First 1
if ($excelFile) {
$excel = New-Object -ComObject Excel.Application -Property #{Visible = $false}
# Open the file
$workbook = $excel.Workbooks.Open($excelFile.FullName)
# Activate the first worksheet
$sheet = $workbook.Sheets.Item(1)
[void]$sheet.Cells.Item(1, 1).EntireRow.Delete() # Delete the first row
[void]$sheet.Cells.Item(1, 1).EntireRow.Delete() # Delete the 2 row
[void]$sheet.Cells.Item(1, 1).EntireRow.Delete() # Delete the 3 row
[void]$sheet.Cells.Item(1, 1).EntireRow.Delete() # Delete the 4 row
[void]$sheet.Cells.Item(1, 1).EntireRow.Delete() # Delete the 5 row
$workbook.SaveAs($excelOut,6)
# Close workbook and save changes
$workbook.Close($true)
# Quit Excel
$excel.Quit()
# clean-up Com objects
[System.Runtime.Interopservices.Marshal]::ReleaseComObject($sheet) | Out-Null
[System.Runtime.Interopservices.Marshal]::ReleaseComObject($workbook) | Out-Null
[System.Runtime.Interopservices.Marshal]::ReleaseComObject($excel) | Out-Null
$headers = 'Title','First Name','Surname','Number','DoB','Amount','EmployeeNo','Location'
# import the csv file and select all the above headers plus one that is created using a calculated property
$csv = Import-Csv -Path $excelOut -Header $headers -UseCulture | Select-Object *, #{Name = 'Paycentre'; Expression = {$defaultValue}}
Write-Host "Creating completed csv file '$completedFile'"
$csv | Export-Csv -Path $completedFile -UseCulture -Force -NoTypeInformation
}
else {
Write-Warning "Could not find a file using filter '$filter' in path '$path'"
}
I'm using the -UseCulture switch on Import-Csv and Export-Csv in order to match the delimiter character Excel is using on your system
Hope that helps