How can I convert a PPT file into HTML using C# or VB.NET?

In C# and VB.NET, you can use the PowerPoint Interop library to convert PPT files to HTML. Here is a simple sample code:

using System;
using Microsoft.Office.Interop.PowerPoint;

namespace PPTtoHTMLConverter
{
    class Program
    {
        static void Main(string[] args)
        {
            Application pptApp = new Application();
            Presentation presentation = pptApp.Presentations.Open(@"C:\path\to\your\presentation.pptx");

            string htmlFileName = @"C:\path\to\output\html\file.html";
            presentation.SaveAs(htmlFileName, PpSaveAsFileType.ppSaveAsHTML, MsoTriState.msoTrue);

            Console.WriteLine("PPT file converted to HTML successfully!");

            presentation.Close();
            pptApp.Quit();
        }
    }
}

Please note that the above code requires Microsoft PowerPoint software to be installed on the computer and reference to the PowerPoint Interop library. Alternatively, third-party libraries or online tools can be used to achieve PowerPoint to HTML conversion.