"a" Does not contain a definition for"b" and no extension method ' b ' accepting a first argument of type

Question

I got an error which i cant fix:

Error 1 'System.Windows.Forms.Label' does not contain a definition for 'Copy' 
and no extension method 'Copy' accepting a first argument of     
type'System.Windows.Forms.Label' 
could be found (are you missing a using directive or an assembly reference?)
//path 156  22 FileWatcherEigen

That was my error. Can someone help me and explain to me what went wrong?

This is my code:

using System;
using System.IO;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{

public partial class Form1 : Form
{
    private bool pause = false;
    private bool cut1 = false;
    private bool copy1 = false;

    public Form1()

    {
        InitializeComponent();
    }



    // The lines with performed actions of a file
  private void fileSystemWatcher1_Created(object sender,System.IO.FileSystemEventArgs e)
    {
        if (!pause)
        {
            listBox1.Items.Add("File Created> " + e.FullPath + " -Date:" + DateTime.Now);
        }
    }

    private void fileSystemWatcher1_Changed(object sender, System.IO.FileSystemEventArgs e)
    {
        if (!pause)
        {
            listBox1.Items.Add("File Changed> " + e.FullPath + " -Date:" + DateTime.Now);
        }
    }
    private void fileSystemWatcher1_Deleted(object sender, System.IO.FileSystemEventArgs e)
    {
        if (!pause)
        {
            listBox1.Items.Add("File Deleted> " + e.FullPath + " -Date:" + DateTime.Now);
        }
    }

    private void fileSystemWatcher1_Renamed(object sender, System.IO.RenamedEventArgs e)
    {
        if (!pause)
        {
            listBox1.Items.Add("File Renamed> " + e.FullPath + " -Date:" + DateTime.Now);
        }
    }

    private void fileSystemWatcher2_Changed(object sender, System.IO.FileSystemEventArgs e)
    {
        if (!pause)
        {
            listBox1.Items.Add("File Changed> " + e.FullPath + " -Date:" + DateTime.Now);
        }
    }

    private void fileSystemWatcher2_Created(object sender, System.IO.FileSystemEventArgs e)
    {
        if (!pause)
        {
            listBox1.Items.Add("File Created> " + e.FullPath + " -Date:" + DateTime.Now);
        }
    }

    private void fileSystemWatcher2_Deleted(object sender, System.IO.FileSystemEventArgs e)
    {
        if (!pause)
        {
            listBox1.Items.Add("File Deleted> " + e.FullPath + " -Date:" + DateTime.Now);
        }
    }

    private void fileSystemWatcher2_Renamed(object sender, System.IO.RenamedEventArgs e)
    {
        if (!pause)
        {
            listBox1.Items.Add("File Renamed> " + e.FullPath + " -Date:" + DateTime.Now);
        }
    }

    //1st directory
    private void button2_Click(object sender, EventArgs e)
    {
        if (dlgOpenDir.ShowDialog() == DialogResult.OK)
        {
            fileSystemWatcher1.EnableRaisingEvents = false;  // Stop watching
            fileSystemWatcher1.IncludeSubdirectories = true;
            fileSystemWatcher1.Path = dlgOpenDir.SelectedPath;
            textBox1.Text = dlgOpenDir.SelectedPath;         // Text of textBox2 = Path of fileSystemWatcher2
            fileSystemWatcher1.EnableRaisingEvents = true;   // Begin watching
        }
    }
    //2nd directory
    private void button3_Click(object sender, EventArgs e)
    {
        if (dlgOpenDir.ShowDialog() == DialogResult.OK)
        {
            fileSystemWatcher2.EnableRaisingEvents = false;  // Stop watching
            fileSystemWatcher2.IncludeSubdirectories = true;
            fileSystemWatcher2.Path = dlgOpenDir.SelectedPath;
            textBox2.Text = dlgOpenDir.SelectedPath;         // Text of textBox2 = Path of fileSystemWatcher2
            fileSystemWatcher2.EnableRaisingEvents = true;   // Begin watching
        }
    }
    //log
    private void button1_Click(object sender, EventArgs e)
    {

        DialogResult resDialog = dlgSaveFile.ShowDialog();
        if (resDialog.ToString() == "OK")
        {
            FileInfo fi = new FileInfo(dlgSaveFile.FileName);
            StreamWriter sw = fi.CreateText();
            foreach (string sItem in listBox1.Items)
            {
                sw.WriteLine(sItem);
            }
            sw.Close();
        }
    }
    //pause watching
    private void pause_button_Click(object sender, EventArgs e)
    {
        if (!pause)
        {
            pause = true;
            pause_button.Text = "Unpause";
        }
        else
        {
            pause = false;
            pause_button.Text = "Pause Watching";
        }
    }
    //clear listbox
    private void clear_button_Click(object sender, EventArgs e)
    {
        listBox1.Items.Clear(); 
    }

    private void Transfer_Click(object sender, EventArgs e)
    {
        if (copy1)
        {
            File.Copy(FileBrowseBox.Text, Path.Combine(DestinationBox.Text, Path.ChangeExtension(FileNameBox.Text, Path.GetExtension(FileBrowseBox.Text))));
        }

        }

    private void Browse_file_Click(object sender, EventArgs e)
    {
        DialogResult resDialog = openFileDialog1.ShowDialog();
        if (resDialog == DialogResult.OK)
        {
            FileBrowseBox.Text = openFileDialog1.FileName;
        }
    }

    private void Browse_destination_Click(object sender, EventArgs e)
    {
        DialogResult resDialog = folderBrowserDialog1.ShowDialog();
        if (resDialog == DialogResult.OK)
        {
            DestinationBox.Text = folderBrowserDialog1.SelectedPath;
        }

    }

    private void CopyButton_CheckedChanged(object sender, EventArgs e)
    {
        copy1 = true;
    }

}
}

It says the problem is within this part:

 File.Copy(FileBrowseBox.Text, Path.Combine(DestinationBox.Text, Path.ChangeExtension(FileNameBox.Text, Path.GetExtension(FileBrowseBox.Text))));

I have tried to find it on this forum but i couldn't really find the answer or solution

It does work with this code:

using System;
using System.IO;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
public partial class Form1 : Form
{
    private bool cut = false;
    private bool copy = false;
    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
{
    File.Copy(FileBrowseBox.Text, Path.Combine(DestinationBox.Text, Path.ChangeExtension(FileBox.Text, Path.GetExtension(FileBrowseBox.Text))));
    label2.Text = "File Transfer Succeeded";
}

    private void button2_Click(object sender, EventArgs e)
    {
        DialogResult resDialog = openFileDialog1.ShowDialog();
        if (resDialog == DialogResult.OK)
        {
            FileBrowseBox.Text = openFileDialog1.FileName;
            label2.Text = "";
        }
    }

    private void button3_Click(object sender, EventArgs e)
    {
        DialogResult resDialog = folderBrowserDialog1.ShowDialog();
        if (resDialog == DialogResult.OK)
        {
            DestinationBox.Text = folderBrowserDialog1.SelectedPath;
            label2.Text = "";
        }
    }

    private void radioButton1_CheckedChanged(object sender, EventArgs e)
    {
        copy = true;
    }

    private void radioButton2_CheckedChanged(object sender, EventArgs e)
    {
        cut = true;
    }
}
}

Answer 1

You're getting this error because you have a label named File on your form that's being referenced rather than System.IO.File. You can either rename the Label, which I'd recommend, or you can use the fully qualified path of System.IO.File.Copy instead.

Answer 2

Apparently you have a Label named File. It shadows the System.IO.File class and causes the error. Specifying full class name should eliminate the problem:

System.IO.File.Copy(...