Issue regarding open word file and read only mode using c# & MS-word interop

Question

i am programmatically open a word file for search and highlight keyword. my routine is working fine. the problem is when i am opening the file programmatically then a dialog come and ask me to open file in read only mode. the dialog look like below one
actually i do not want to open the file in read only mode because people can open and like to change and save. so guide me what i can do to not to open the file in read only mode.
here is my full code. just have a look and tell me what is wrong in my code or tell me any trick as a result i can open the file not in read only mode. here is my code.
private void button1_Click(object sender, EventArgs e)
            object fileName = "";
            string filePath = "";
            string strSaveasPath = "";
            DialogResult result = openFileDialog1.ShowDialog();
            if (result == DialogResult.OK)
                fileName = openFileDialog1.FileName;
                //strSaveasPath = Path.GetDirectoryName(path.ToString());
            //fileName = "Z:\\C0000000003.doc";
            List<string> _list = new List<string>();
            _list.Add("tridip");
            _list.Add("arijit");
            //object fileName = "D:\\CVArchievePath\\C0000000001.doc";
            object textToFind = "test";
            object readOnly = false;
            Word.Application word = new Word.Application();
            Word.Document doc = new Word.Document();
            object missing = Type.Missing;
            try
                doc = word.Documents.Open(ref fileName, ref missing, ref readOnly,
                                          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);
                doc.Activate();
                object matchPhrase = false;
                object matchCase = false;
                object matchPrefix = false;
                object matchSuffix = false;
                object matchWholeWord = false;
                object matchWildcards = false;
                object matchSoundsLike = false;
                object matchAllWordForms = false;
                object matchByte = false;
                object ignoreSpace = false;
                object ignorePunct = false;
                object highlightedColor = Word.WdColor.wdColorGreen;
                object textColor = Word.WdColor.wdColorLightOrange;
                object missingp = false;
                Word.Range range = doc.Range();
                foreach (string line in _list)
                    textToFind = line;
                    bool highlighted = range.Find.HitHighlight(ref textToFind,
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,
ref missing,
ref missing,
ref missing,
ref missing);
                System.Diagnostics.Process.Start(fileName.ToString());
            catch (Exception ex)
                Console.WriteLine("Error : " + ex.Message);
                //Console.ReadKey(true);
            finally
                //doc.Close(missing, missing, missing);
                if(doc!=null)
                    System.Runtime.InteropServices.Marshal.ReleaseComObject(doc);
                if (word != null)
                    System.Runtime.InteropServices.Marshal.ReleaseComObject(word);
                word = null;
                doc = null;
                GC.Collect();
                GC.WaitForPendingFinalizers();

Answer 1

I know it's a very old issue and I reached to this page looking for a solution. Finally, I have found a fix to this problem.
The problem is that we create an instance of Word and do not close it correctly. This makes program believe that the file is already open and hence you're getting the respective message of file being locked by you.
Set the visibility of your application to true and then when you close it both file and instance should close and you will not get the problem again.