Get all the text in all slides in a presentation

    // Open the presentation as read-only.
        using (PresentationDocument presentationDocument = PresentationDocument.Open(presentationFile, false))
    {
        // Insert other code here.
    }

    Using presentationDocument As PresentationDocument = PresentationDocument.Open(presentationFile, False)
        ' Insert other code here.
    End Using

    Console.Write("Please enter a presentation file name without extension: ");
    string fileName = Console.ReadLine();
    string file = @"C:\Users\Public\Documents\" + fileName + ".pptx";
    int numberOfSlides = CountSlides(file);
    System.Console.WriteLine("Number of slides = {0}", numberOfSlides);
    string slideText;
    for (int i = 0; i < numberOfSlides; i++)
    {
        GetSlideIdAndText(out slideText, file, i);
        System.Console.WriteLine("Slide #{0} contains: {1}", i + 1, slideText);
    }
    System.Console.ReadKey();

    Console.Write("Please enter a presentation file name without extension: ")
    Dim fileName As String = System.Console.ReadLine()
    Dim file As String = "C:\Users\Public\Documents\" + fileName + ".pptx"
    Dim numberOfSlides As Integer = CountSlides(file)
    System.Console.WriteLine("Number of slides = {0}", numberOfSlides)
    Dim slideText As String = Nothing
    For i As Integer = 0 To numberOfSlides - 1
        GetSlideIdAndText(slideText, file, i)
        System.Console.WriteLine("Slide #{0} contains: {1}", i + 1, slideText)
    Next
    System.Console.ReadKey()

using DocumentFormat.OpenXml;
using DocumentFormat.OpenXml.Packaging;
using DocumentFormat.OpenXml.Presentation;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using A = DocumentFormat.OpenXml.Drawing;

if (args is [{ } sldText, { } slideIndex])
{
    GetSlideIdAndText(out string text, sldText, int.Parse(slideIndex));
}

if (args is [{ } presentationFile])
{
    CountSlides(presentationFile);
}

static int CountSlides(string presentationFile)
{
    // Open the presentation as read-only.
    using (PresentationDocument presentationDocument = PresentationDocument.Open(presentationFile, false))
    {
        // Pass the presentation to the next CountSlides method
        // and return the slide count.
        return CountSlidesFromPresentation(presentationDocument);
    }
}

// Count the slides in the presentation.
static int CountSlidesFromPresentation(PresentationDocument presentationDocument)
{
    // Check for a null document object.
    if (presentationDocument is null)
    {
        throw new ArgumentNullException("presentationDocument");
    }

    int slidesCount = 0;

    // Get the presentation part of document.
    PresentationPart? presentationPart = presentationDocument.PresentationPart;
    // Get the slide count from the SlideParts.
    if (presentationPart is not null)
    {
        slidesCount = presentationPart.SlideParts.Count();
    }

    // Return the slide count to the previous method.
    return slidesCount;
}

static void GetSlideIdAndText(out string sldText, string docName, int index)
{
    using (PresentationDocument ppt = PresentationDocument.Open(docName, false))
    {
        // Get the relationship ID of the first slide.
        PresentationPart? part = ppt.PresentationPart;
        OpenXmlElementList slideIds = part?.Presentation?.SlideIdList?.ChildElements ?? default;

        if (part is null || slideIds.Count == 0)
        {
            sldText = "";
            return;
        }

        string? relId = ((SlideId)slideIds[index]).RelationshipId;

        if (relId is null)
        {
            sldText = "";
            return;
        }

        // Get the slide part from the relationship ID.
        SlidePart slide = (SlidePart)part.GetPartById(relId);

        // Build a StringBuilder object.
        StringBuilder paragraphText = new StringBuilder();

        // Get the inner text of the slide:
        IEnumerable<A.Text> texts = slide.Slide.Descendants<A.Text>();
        foreach (A.Text text in texts)
        {
            paragraphText.Append(text.Text);
        }
        sldText = paragraphText.ToString();
    }
}

Imports System.Text
Imports DocumentFormat.OpenXml
Imports DocumentFormat.OpenXml.Packaging
Imports DocumentFormat.OpenXml.Presentation
Imports A = DocumentFormat.OpenXml.Drawing


Module MyModule

    Sub Main(args As String())
    End Sub

    Public Function CountSlides(ByVal presentationFile As String) As Integer
        ' Open the presentation as read-only.
        Using presentationDocument__1 As PresentationDocument = PresentationDocument.Open(presentationFile, False)
            ' Pass the presentation to the next CountSlides method
            ' and return the slide count.
            Return CountSlides(presentationDocument__1)
        End Using
    End Function

    ' Count the slides in the presentation.
    Public Function CountSlides(ByVal presentationDocument As PresentationDocument) As Integer
        ' Check for a null document object.
        If presentationDocument Is Nothing Then
            Throw New ArgumentNullException("presentationDocument")
        End If

        Dim slidesCount As Integer = 0

        ' Get the presentation part of document.
        Dim presentationPart As PresentationPart = presentationDocument.PresentationPart
        ' Get the slide count from the SlideParts.
        If presentationPart IsNot Nothing Then
            slidesCount = presentationPart.SlideParts.Count()
        End If
        ' Return the slide count to the previous method.
        Return slidesCount
    End Function

    Public Sub GetSlideIdAndText(ByRef sldText As String, ByVal docName As String, ByVal index As Integer)
        Using ppt As PresentationDocument = PresentationDocument.Open(docName, False)
            ' Get the relationship ID of the first slide.
            Dim part As PresentationPart = ppt.PresentationPart
            Dim slideIds As OpenXmlElementList = part.Presentation.SlideIdList.ChildElements

            Dim relId As String = TryCast(slideIds(index), SlideId).RelationshipId

            ' Get the slide part from the relationship ID.
            Dim slide As SlidePart = DirectCast(part.GetPartById(relId), SlidePart)
            ' Build a StringBuilder object.
            Dim paragraphText As New StringBuilder()

            ' Get the inner text of the slide:
            Dim texts As IEnumerable(Of A.Text) = slide.Slide.Descendants(Of A.Text)()
            For Each text As A.Text In texts
                paragraphText.Append(text.Text)
            Next
            sldText = paragraphText.ToString()
        End Using
    End Sub
End Module