CopyMyFile.cs

using System;
using System.Windows.Forms;
using System.IO;

namespace CopyMyFile
{
    static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Form1());
        }
    }

    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            string[] drives = Directory.GetLogicalDrives();//C:  D:  E: WIN API
            listBox1.Items.AddRange(drives);
            listBox2.Items.AddRange(drives);
        }

        private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
        {

        }

        private void listBox2_SelectedIndexChanged(object sender, EventArgs e)
        {

        }

        private void listBox1_SelectedIndexChanged(object sender, MouseEventArgs e)
        {
            int index = listBox1.SelectedIndex;//UI
            string path = listBox1.Items[index].ToString();//UI
            //////////////////////////////////////
            string[] dirs = Directory.GetDirectories(path);//WIN API
            string[] files = Directory.GetFiles(path);//WIN API
            //////////////////////////////////////
            listBox1.Items.Clear();
            listBox1.Items.AddRange(dirs); //UI
            listBox1.Items.AddRange(files);//UI
        }

        private void listBox2_MouseDoubleClick(object sender, MouseEventArgs e)
        {
            int index = listBox2.SelectedIndex;//UI
            string path = listBox2.Items[index].ToString();//UI
            //////////////////////////////////////
            string[] dirs = Directory.GetDirectories(path);//WIN API
            string[] files = Directory.GetFiles(path);//WIN API
            //////////////////////////////////////
            listBox2.Items.Clear();
            listBox2.Items.AddRange(dirs); //UI
            listBox2.Items.AddRange(files);//UI
        }

        private void button1_Click(object sender, EventArgs e)
        {
            int index1 = listBox1.SelectedIndex;//UI
            string path1 = listBox1.Items[index1].ToString();//UI

            int index2 = listBox2.SelectedIndex;//UI
            string path2 = listBox2.Items[index2].ToString();//UI
            string filename = Path.GetFileName(path1);
            File.Copy(path1, path2 + "\\" + filename);
        }
    }

    partial class Form1
    {
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows Form Designer generated code

        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.splitContainer1 = new System.Windows.Forms.SplitContainer();
            this.listBox1 = new System.Windows.Forms.ListBox();
            this.listBox2 = new System.Windows.Forms.ListBox();
            this.button1 = new System.Windows.Forms.Button();
            this.button2 = new System.Windows.Forms.Button();
            ((System.ComponentModel.ISupportInitialize)(this.splitContainer1)).BeginInit();
            this.splitContainer1.Panel1.SuspendLayout();
            this.splitContainer1.Panel2.SuspendLayout();
            this.splitContainer1.SuspendLayout();
            this.SuspendLayout();
            // 
            // splitContainer1
            // 
            this.splitContainer1.Dock = System.Windows.Forms.DockStyle.Fill;
            this.splitContainer1.Location = new System.Drawing.Point(0, 0);
            this.splitContainer1.Name = "splitContainer1";
            // 
            // splitContainer1.Panel1
            // 
            this.splitContainer1.Panel1.Controls.Add(this.button1);
            this.splitContainer1.Panel1.Controls.Add(this.listBox1);
            // 
            // splitContainer1.Panel2
            // 
            this.splitContainer1.Panel2.Controls.Add(this.button2);
            this.splitContainer1.Panel2.Controls.Add(this.listBox2);
            this.splitContainer1.Size = new System.Drawing.Size(578, 421);
            this.splitContainer1.SplitterDistance = 274;
            this.splitContainer1.TabIndex = 0;
            // 
            // listBox1
            // 
            this.listBox1.Dock = System.Windows.Forms.DockStyle.Fill;
            this.listBox1.FormattingEnabled = true;
            this.listBox1.Location = new System.Drawing.Point(0, 0);
            this.listBox1.Name = "listBox1";
            this.listBox1.Size = new System.Drawing.Size(274, 421);
            this.listBox1.TabIndex = 0;
            this.listBox1.MouseDoubleClick += new System.Windows.Forms.MouseEventHandler(this.listBox1_SelectedIndexChanged);
            // 
            // listBox2
            // 
            this.listBox2.Dock = System.Windows.Forms.DockStyle.Fill;
            this.listBox2.FormattingEnabled = true;
            this.listBox2.Location = new System.Drawing.Point(0, 0);
            this.listBox2.Name = "listBox2";
            this.listBox2.Size = new System.Drawing.Size(300, 421);
            this.listBox2.TabIndex = 0;
            this.listBox2.MouseDoubleClick += new System.Windows.Forms.MouseEventHandler(this.listBox2_MouseDoubleClick);
            // 
            // button1
            // 
            this.button1.Dock = System.Windows.Forms.DockStyle.Right;
            this.button1.Location = new System.Drawing.Point(242, 0);
            this.button1.Name = "button1";
            this.button1.Size = new System.Drawing.Size(32, 421);
            this.button1.TabIndex = 1;
            this.button1.Text = ">";
            this.button1.UseVisualStyleBackColor = true;
            this.button1.Click += new System.EventHandler(this.button1_Click);
            // 
            // button2
            // 
            this.button2.Dock = System.Windows.Forms.DockStyle.Right;
            this.button2.Location = new System.Drawing.Point(265, 0);
            this.button2.Name = "button2";
            this.button2.Size = new System.Drawing.Size(35, 421);
            this.button2.TabIndex = 1;
            this.button2.Text = "<";
            this.button2.UseVisualStyleBackColor = true;
            // 
            // Form1
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(578, 421);
            this.Controls.Add(this.splitContainer1);
            this.Name = "Form1";
            this.Text = "Browser";
            this.Load += new System.EventHandler(this.Form1_Load);
            this.splitContainer1.Panel1.ResumeLayout(false);
            this.splitContainer1.Panel2.ResumeLayout(false);
            ((System.ComponentModel.ISupportInitialize)(this.splitContainer1)).EndInit();
            this.splitContainer1.ResumeLayout(false);
            this.ResumeLayout(false);

        }

        #endregion

        private System.Windows.Forms.SplitContainer splitContainer1;
        private System.Windows.Forms.ListBox listBox1;
        private System.Windows.Forms.ListBox listBox2;
        private System.Windows.Forms.Button button1;
        private System.Windows.Forms.Button button2;
    }
}