Highlight duplicate question in MS Word using C# in ASP.Net

Hi PRA,

Please refer below code

HTML

<div>
    <asp:FileUpload ID="FileUpload1" runat="server" />
    <asp:Button ID="btnUpload" runat="server" Text="Upload" OnClick="Upload" />
</div>

C#

protected void Upload(object sender, EventArgs e)
{
    if (this.FileUpload1.HasFile)
    {
        Application word = new Application();
        Document doc = new Document();
        string filePath = Server.MapPath("~/Word/") + Path.GetFileName(FileUpload1.PostedFile.FileName);
        FileUpload1.SaveAs(filePath);
        object missing = System.Type.Missing;
        object fileName = filePath;
        doc = word.Documents.Open(ref fileName,
                ref missing, ref missing, ref missing, ref missing,
                ref missing, ref missing, ref missing, ref missing,
                ref missing, ref missing, ref missing, ref missing,
                ref missing, ref missing, ref missing);        
        List<string> data = new List<string>();
        for (int i = 0; i < doc.Paragraphs.Count; i++)
        {
            string temp = doc.Paragraphs[i + 1].Range.Text.Trim();
            if (temp != string.Empty)
                data.Add(temp);
        }
        var duplicateQuestions = data.Where(x => x.Contains("@")).Select(y => y.Split('.')[1].Trim()).GroupBy(x => x).Where(z => z.Count() > 1).Select(k => k.Key);
        foreach (string item in duplicateQuestions)
        {
            int count = 0;
            for (int i = 0; i < doc.Paragraphs.Count; i++)
            {
                string temp = doc.Paragraphs[i + 1].Range.Text.Trim();
                if (temp.Split('.').Length > 1)
                {
                    if (item == temp.Split('.')[1].Trim())
                    {
                        count++;
                    }
                    if (item == temp.Split('.')[1].Trim() && count > 1)
                    {
                        doc.Paragraphs[i + 1].Range.Font.ColorIndex = Microsoft.Office.Interop.Word.WdColorIndex.wdGreen;
                    }
                }
            }
        }
        doc.Save();
        doc.Close(ref missing, ref missing, ref missing);
        ((_Application)word).Quit();
    }
}

ScreenShot

Hope this works for you