无法访问文件

Question

I can't seem to get access to the file I'm working with in the program I'm writing. I'm not sure how exactly to work this since I want my program to open a file of your choice, which it does, then I want it to be able to take in info into an arrary, which it does, then from there, write that information from the array to the file you opened up. When I try some code to start working on it it tells me, "The process cannot access the file 'file' because it is being used by another process." Here is what I have so far. Please let me know. Thank you. The problematic areas is the Save_Click section of the code where I wrote "This is a test" Thanks.

     public partial class ListingSearch : Form
{
    string line;
    DialogResult result;
    string fileName;
    int i = 0;
    string[] first = new string[100];
    string[] last = new string [100];
    string[] phone = new string [100];
    string[] grade = new string [100];

    public ListingSearch()
    {
        InitializeComponent();
        MessageBox.Show("Please be sure to open a file before beginning");
    }

    private void OpenFile_Click(object sender, EventArgs e)
    {
        using (OpenFileDialog filechooser = new OpenFileDialog())
        {
            result = filechooser.ShowDialog();
            fileName = filechooser.FileName;
            System.IO.StreamReader file =
                new System.IO.StreamReader(fileName);

            while ((line = file.ReadLine()) != null)
            {
                string[] words = File.ReadAllText(fileName).Split(new string[] { "\n", "\r\n", ":" }, StringSplitOptions.RemoveEmptyEntries);
                //firstName.Text = words[4];
                //lastName.Text = words[5];
                //telephone.Text = words[6];
                //GPA.Text = words[7];
            }
            Read.Enabled = true;
       }
    }

    private void Save_Click(object sender, EventArgs e)
    {
        File.AppendAllText(fileName, "This is a test");
    }

    private void Read_Click(object sender, EventArgs e)
    {
        MessageBox.Show(fileName);
        MessageBox.Show(File.ReadAllText(fileName));
    }

    private void info_Click(object sender, EventArgs e)
    {
        first[i] = firstName.Text;
        firstName.Text = " ";
        last[i] = lastName.Text;
        lastName.Text = " ";
        phone[i] = telephone.Text;
        telephone.Text = " ";
        grade[i] = GPA.Text;
        GPA.Text = " ";
        i++;
    }

    private void displayinfo_Click(object sender, EventArgs e)
    {
        if (i == 0)
            MessageBox.Show("Nothing to display!");
        else
        for (int j = 0; j < i; j++)
        {
            MessageBox.Show(first[j] + " " + last[j] + "\r" + phone[j] + "\r" + grade[j]);
        }
    }

Answer 1

You get error here

File.ReadAllText(fileName) 

because you open same file before it here

System.IO.StreamReader file = new System.IO.StreamReader(fileName);

Answer 2

You need to close the file after you are finished reading it. Also, not sure why you are opening the file at all, since you subsequently use File.ReadAllText which will handle opening and closing the file all on its own.

Seems like your OpenFile_click event should just look like this:

   using (OpenFileDialog filechooser = new OpenFileDialog())
    {
        result = filechooser.ShowDialog();
        fileName = filechooser.FileName;

        string[] words = File.ReadAllText(fileName).Split(new string[] { "\n", "\r\n", ":" }, StringSplitOptions.RemoveEmptyEntries);

        Read.Enabled = true;
    }

Answer 3

You haven't closed your StreamReader. C# will lock the file until you do. Or you could use a StreamWriter after you closed your StreamReader