Question

I’m getting the above error. I saw other similar posts on this error but I don’t seem to find where the problem is. I changed my class type to static and the error resists. This is the entire code to my main form class:

I Edited my class. This is how it looks like now and the error has changed to:Missing partial modifier on declaration of type ‘PhoneFind.frmMain’; another partial declaration of this type exists.

namespace PhoneFind
{
    public partial class frmMain : Form
    {
        // the path to the temporary file to store the webresponse
        String path = "c:\\Temp\\webresponse.txt";
        public frmMain()
        {
            InitializeComponent();
            comboSelectSearchEngine.SelectedIndex = 0;
            ofdPhones.Filter = "txt files (*.txt)|*.txt";
            listbxMessages.Items.Clear();
            addItemToListBox(listbxMessages, "Welcome to ActionBase Phone Find!");
            addItemToListBox(listbxMessages, "Select the file containing the numbers.");
            radioNumbers.Checked = true;
        }

        private void frmMain_Load(object sender, EventArgs e)
        {

        }

        private void btnLoadFile_Click(object sender, EventArgs e)
        {
            if (ofdPhones.ShowDialog() == System.Windows.Forms.DialogResult.OK)
            {
                txtFile.Text = ofdPhones.FileName;

                // Read the file line by line and add the numbers to the numbers listbox.
                listbxNumbers.Items.Clear();
                String line;
                int numbersCounter = 0;
                System.IO.StreamReader file = new System.IO.StreamReader(ofdPhones.FileName);
                while ((line = file.ReadLine()) != null)
                {
                    listbxNumbers.Items.Add(line.Trim());
                    numbersCounter++;
                }
                addItemToListBox(listbxMessages, ofdPhones.FileName + " loaded.");
                addItemToListBox(listbxMessages, numbersCounter + " records found in the file.");

            }
        }

        // add item to the listbox and move scroll to the end of the listbox for the latest messages to be visibile to the viewer
        private void addItemToListBox(ListBox listbox, String item)
        {
            listbox.Items.Add(item);
            listbox.SelectedIndex = (listbox.Items.Count - 1);
        }

        private void radioNumbers_CheckedChanged(object sender, EventArgs e)
        {
            if (!radioNumbers.Checked)
            {
                grpbxNumbers.Text = "Names and Addresses";
            }
            else
            {
                grpbxNumbers.Text = "Numbers";
            }
        }

        private void btnRun_Click(object sender, EventArgs e)
        {
            if (listbxNumbers.Items.Count == 0)
            {
                MessageBox.Show("No records have been loaded." + "\n" + "Use the browse button to load records.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
            else if (!CheckForInternetConnection())
            {
                MessageBox.Show("No internet connection.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
            else
            {
                String response;
                switch (comboSelectSearchEngine.SelectedIndex)
                {
                    case 0: // Hitta.se
                        foreach (String item in listbxNumbers.Items)
                        {
                            WebRequestObj request = new WebRequestObj(item, "hitta");
                            response = request.sendRequest();
                            if (response.Equals("Error"))
                            {
                                addItemToListBox(listbxMessages, "Error sending '" + item + "' to the server.");
                            }
                            else
                            {
                                //create a temporary file to work on the response
                                StreamWriter sw;
                                if (!File.Exists(path)) {
                                    sw = File.CreateText(path);
                                }
                                try
                                {
                                    File.WriteAllText(path, String.Empty); // clear the content of the file
                                    sw = File.AppendText(path);
                                    sw.WriteLine(response);
                                    sw.Flush();
                                    sw.Close();
                                    String s = findResultType(path);
                                    MessageBox.Show(s);
                                }
                                catch (IOException ioe)
                                {
                                    MessageBox.Show(ioe.Message,"Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                                }


                            }
                        }
                        break;
                }
            }
        }

        public bool CheckForInternetConnection()
        {
            try
            {
                using (var client = new System.Net.WebClient())
                using (var stream = client.OpenRead("http://www.google.com"))
                {
                    return true;
                }
            }
            catch
            {
                return false;
            }
        }

        /*
         * findResultType
         * gets the web response and finds out if the matching result of the search termis one of the following:
         * 1. one person (oneperson)
         * 2. one company (onecompany)
         * 3. more than one person, no company (manypersonnocompany)
         * 4. no person, more than one company (nopersonmanycompany)
         * 5. more than one person, more than one company (manypersonmanycompany)
         * 6. no person, no company (nopersonnocompany)
         */
        public String findResultType(String reponsepath)
        {                   
            HtmlAgilityPack.HtmlDocument doc = new HtmlAgilityPack.HtmlDocument();
            doc.Load(reponsepath);
            List<String> itemList = new List<String>();
            IEnumerable<String> v = null;
            var item = doc.DocumentNode.SelectNodes("//body[@id='person']");

            if (item != null)
            {
                v = item.Select(p => p.InnerText);
                itemList = v.ToList();
                if (itemList.Count == 1)
                    return "oneperson";
            }
            else
            {
                item = doc.DocumentNode.SelectNodes("//body[@id='company']");
                if (item != null)
                {
                    v = item.Select(p => p.InnerText);
                    itemList = v.ToList();
                    if (itemList.Count == 1)
                        return "onecompany";
                }
            }

            //for (int i = 0; i < itemList.Count; i++)
            //{
            //    MessageBox.Show(itemList[i]);
            //    //console.writeline(itemlist[i]);
            //}
            //console.writeline(itemlist.count + " results found.");
            return "";
        }
    }
}

Answer 1

This is your first problem:

public static class frmMain : Form

You can’t derive a static class from another class. A static class always implicitly derives from Object. You also can’t have non-static members in static classes.

So basically, you can’t put your extension method in your frmMain class (which should be renamed to follow .NET naming conventions and to be somewhat more descriptive at the same time). Why did you want to put the extension method in that class anyway?

I can’t even see an extension method in the code you’ve posted – did you remove it? Is it in some other class you haven’t posted?

Fundamentally, I think you need to take a step back. It sounds like you’ve reacted to the compiler error message without really understanding it fully. Read up on extension methods, read up on what static classes are, until you really understand why you don’t want your form class to be static, and why you do want to make the class that contains your extension method static.