Using powershell to compare excel file headers

Question

I have an XLSM file dynamically created in PowerShell using the code below.

dd-Type -AssemblyName Microsoft.Office.Interop.Excel  
$xl  = [Microsoft.Office.interop.Excel.XLFileFormat]::xlOpenXMLWorkbookMacroEnabled  
$xlsm = New-Object -ComObject Excel.Application  
$workbook = $xlsm.workbooks.add()  
$worksheetNew = $workbook.Worksheets.add()  
$sheet1 = $workbook.Worksheets.item(1)  
$sheet1.name = "Source"  
$filepath = 'C:\output\file.xlsm'  
  
  
$sheet1.cells.item(1,1) = "ID"  
$sheet1.cells.item(1,2) = "Firstname"  
$sheet1.cells.item(1,3) = "Surname"  
$sheet1.cells.item(1,4) = "Grade"  
$xlsm.ActiveWorkbook.SaveAs("$filepath",$xl)  
$xlsm.quit()  
[System.Runtime.Interopservices.Marshal]::ReleaseComObject($xlsm) | Out-Null

The code above creates a file with the following column headers.

ID  
Firstname  
Surname  
Grade

What I am trying to achieve is to compare the headers generated in the code above with the headers in the template file, I want to compare column for column (including the column header name) and highlight the differences between what was created in the code and the template file. A screenshot of the template file can be seen below. The column names should be exactly the same and any difference in the column names of missing column names should be highlighted.

The differences in this case are as follows

Grade Score (spelt differently compared to what is in the code)  
City (extra column header in the template file)  
School Name (extra column header in the template file)

I am also looking to have a count of template headers and generated files to see if they match.

What I have so far can be seen below.

$ExcelFile = "C:\output\file.xlsm"  
$excel = New-Object -ComObject Excel.Application  
$excel.visible = $true  
$Workbook = $excel.workbooks.open($ExcelFile)  
$Worksheets = $Workbook.worksheets  
$Worksheet = $Workbook.worksheets.Item(1)  
  
Function Read-Headers {  
    # Parameters: Excel worksheet  
    # Returns: Hash table of the contents of each cell in the first row and the  
    #    corresponding column number  
    # Note: Processes until first blank cell  
        Param ($Worksheet)      
        $Headers =@{}  
        $column = 1  
        Do {  
            $Header = $Worksheet.cells.item(1,$column).text  
            If ($Header) {  
                $Headers.add($Header, $column)  
                $column++  
            }  
        } until (!$Header)  
        $Headers  
    }  
      
    $Headers = Read-Headers $Worksheet  
  
$Headers

This shows me the headers and their positions.

The challenge now is how do I compare it programmatically ?

Answer

Hi @MrFlinstone ,

Does this work for you?

Add-Type -AssemblyName Microsoft.Office.Interop.Excel  
$Excel = New-Object -ComObject Excel.Application  
$FilePath = 'C:\output\file.xlsm'  
$TemplatePath = 'C:\output	emplate.xlsm'  
$FileBook = $Excel.workbooks.Open($filepath)  
$FileSheet = $FileBook.Worksheets.item(1)  
$FileColumns = $filesheet.UsedRange.Columns.Count  
$FileHeaders = @()  
for($i=1;$i -le $FileColumns;$i++){  
    $FileHeaders += $FileSheet.UsedRange.Cells.Item(1,$i).Text  
}  
$FileBook.Close()  
$Excel.Visible = $true  
$TemplateBook = $Excel.workbooks.Open($TemplatePath)  
$TemplateSheet = $TemplateBook.Worksheets.Item(1)  
$TemplateColumns = $TemplateSheet.UsedRange.Columns.Count  
for($j=1;$j -le $TemplateColumns;$j++){  
    if($TemplateSheet.Cells.Item(1,$j).text -notin $FileHeaders){  
     $TemplateSheet.Cells.Item(1,$j).interior.colorindex = 3    
    }  
}

Best Regards,
Ian Xue

============================================

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Using powershell to compare excel file headers

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