如何从PowerShell向VBA方法传递缺少的可选参数

我有一个Word（Office 2013）文档，我需要将文档的每一页拆分为单独的PDF。所以，我使用PowerShell将其组合在一起

$Word = New-Object -ComObject Word.Application
$Word.Visible = $true

$Doc = $Word.Documents.Open($SourceFile)

for ($pageNo = 1; $pageNo -le 50; $pageNo++)
{
    $OutputFile = $OutputDirectory + "\MyFile_" + $pageNo + ".pdf"

    $Doc.ExportAsFixedFormat($OutputFile, [Microsoft.Office.Interop.Word.WdExportFormat]::wdExportFormatPDF, $false, [Microsoft.Office.Interop.Word.WdExportOptimizeFor]::wdExportOptimizeForPrint, [Microsoft.Office.Interop.Word.WdExportRange]::wdExportFromTo, $pageNo, $pageNo, [Microsoft.Office.Interop.Word.WdExportItem]::wdExportDocumentContent, $false, $false, [Microsoft.Office.Interop.Word.WdExportCreateBookmarks]::wdExportCreateNoBookmarks, $false, $true, $false, $null)
}

$Doc.Close()    
$Word.Quit()

我已经把它设置为最后一个参数，它希望这是对它的引用

[ref] System.Object FixedFormatExtClassPtr

我尝试传入$null，0，每个都有或没有[ref]，但我得到了以下错误：

参数：“15”应该是System.Management.Automation.PSReference。 使用[ref]

---

关于最后一个参数需要传递什么，有什么想法吗？或者，有没有更简单的方法来完成这项任务？

我刚刚发现我做错了什么。对于最后一个参数，我需要使用System.Type.Missing

$Word = New-Object -ComObject Word.Application
$Word.Visible = $true

$Doc = $Word.Documents.Open($SourceFile)
$fixedFromatExtClassPtr = [System.Type]::Missing

for ($pageNo = 1; $pageNo -le 50; $pageNo++)
{
    $OutputFile = $OutputDirectory + "\MyFile_" + $pageNo + ".pdf"

    $Doc.ExportAsFixedFormat($OutputFile, [Microsoft.Office.Interop.Word.WdExportFormat]::wdExportFormatPDF, $false, [Microsoft.Office.Interop.Word.WdExportOptimizeFor]::wdExportOptimizeForPrint, [Microsoft.Office.Interop.Word.WdExportRange]::wdExportFromTo, $pageNo, $pageNo, [Microsoft.Office.Interop.Word.WdExportItem]::wdExportDocumentContent, $false, $false, [Microsoft.Office.Interop.Word.WdExportCreateBookmarks]::wdExportCreateNoBookmarks, $false, $true, $false, [ref]$fixedFromatExtClassPtr)
}

$Doc.Close()    
$Word.Quit()

---

我刚刚发现我做错了什么。对于最后一个参数，我需要使用System.Type.Missing

$Word = New-Object -ComObject Word.Application
$Word.Visible = $true

$Doc = $Word.Documents.Open($SourceFile)
$fixedFromatExtClassPtr = [System.Type]::Missing

for ($pageNo = 1; $pageNo -le 50; $pageNo++)
{
    $OutputFile = $OutputDirectory + "\MyFile_" + $pageNo + ".pdf"

    $Doc.ExportAsFixedFormat($OutputFile, [Microsoft.Office.Interop.Word.WdExportFormat]::wdExportFormatPDF, $false, [Microsoft.Office.Interop.Word.WdExportOptimizeFor]::wdExportOptimizeForPrint, [Microsoft.Office.Interop.Word.WdExportRange]::wdExportFromTo, $pageNo, $pageNo, [Microsoft.Office.Interop.Word.WdExportItem]::wdExportDocumentContent, $false, $false, [Microsoft.Office.Interop.Word.WdExportCreateBookmarks]::wdExportCreateNoBookmarks, $false, $true, $false, [ref]$fixedFromatExtClassPtr)
}

$Doc.Close()    
$Word.Quit()