Combine multiple files into single file

bjPak.cs

// Here is a simple class to pack multiple files into one single file.
// it does not support writeing the files dictionary structure as of yet
// This was made as I needed something quick to pack many csv files.

using System;
using System.Collections.Generic;
using System.IO;

namespace FilePack
{
    class bjPak
    {
        //Each file info
        public struct TFile
        {
            //Filename
            public string Filename;
            //Lenfth of the file
            public int flen;
            //The files data
            public byte[] data;
        }

        //Holds each files info
        private List<TFile> FileFrmt;

        private List<string> Files = new List<string>();

        /// <summary>
        /// Return the number of files
        /// </summary>
        public int FileCount
        {
            get
            {
                return FileFrmt.Count;
            }
        }

        /// <summary>
        /// Remove all file info from FileFrmt List
        /// </summary>
        public void ClearFiles()
        {
            FileFrmt.Clear();
        }

        /// <summary>
        /// Add an array of file names to the Files List
        /// </summary>
        /// <param name="_files"></param>
        public void AddFiles(string[] _files)
        {
            foreach (string lzFile in _files)
            {
                //Check if file is found
                if (!File.Exists(lzFile))
                {
                    throw new Exception("File Not Found:\n" + lzFile);
                }
                else
                {
                    //Add to List
                    Files.Add(lzFile);
                }
            }
        }

        /// <summary>
        /// Add a single file to the files List
        /// </summary>
        /// <param name="Filename"></param>
        public void AddFile(string Filename)
        {
            //Check file is found
            if (!File.Exists(Filename))
            {
                throw new Exception("File Not Found:\n" + Filename);
            }
            else
            {
                //Add to files list
                Files.Add(Filename);
            }
        }

        /// <summary>
        /// Return File info record
        /// </summary>
        /// <param name="index"></param>
        /// <returns></returns>
        public TFile GetFile(int index)
        {
            return FileFrmt[index];
        }

        /// <summary>
        /// Pack all the files in Files list into a single file
        /// </summary>
        /// <param name="Filename"></param>
        public void CreatePack(string Filename)
        {
            try
            {
                using (var fs = File.Create(Filename))
                {
                    using (BinaryWriter br = new BinaryWriter(fs))
                    {
                        foreach (string lzFile in Files)
                        {
                            //Set for next file
                            br.Write(true);
                            //Extract filename only supported at the moment
                            FileInfo fi = new FileInfo(lzFile);
                            //Write filename
                            br.Write(fi.Name);
                            //Get file data
                            byte[] data = File.ReadAllBytes(lzFile);
                            //Write the length of the file
                            br.Write(data.Length);
                            //Write file data bytes to the file
                            br.Write(data);
                        }
                        br.Write(false);
                        br.Close();
                    }

                    fs.Close();
                }
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

        /// <summary>
        /// Opens a pack file and read the contents
        /// </summary>
        /// <param name="Filename"></param>
        public void OpenPack(string Filename)
        {
            TFile f = new TFile();

            try
            {
                //Check if file not found
                if (!File.Exists(Filename))
                {
                    throw new Exception("File Not Found:\n" + Filename);
                }
                else
                {
                    FileFrmt = new List<TFile>();

                    using (var fs = File.OpenRead(Filename))
                    {
                        using (BinaryReader br = new BinaryReader(fs))
                        {
                            //While we have files read and write
                            while (br.ReadBoolean() == true)
                            {
                                //Get filename
                                string lzFile = br.ReadString();
                                f.Filename = lzFile;
                                //Read file length
                                f.flen = br.ReadInt32();
                                //Resize and set data with the file bytes
                                byte[] data = new Byte[f.flen];
                                //Read the bytes
                                data = br.ReadBytes(f.flen);
                                //Set f.data to bytes
                                f.data = data;
                                //Add to FileFrmt record
                                FileFrmt.Add(f);
                            }
                            br.Close();
                        }
                        fs.Close();
                    }

                }
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }
    }
}

example.cs

using System;
using System.Collections.Generic;
using System.Windows.Forms;
using System.IO;

namespace FilePack
{
    public partial class frmmain : Form
    {
        public frmmain()
        {
            InitializeComponent();
        }

        private void cmdPack_Click(object sender, EventArgs e)
        {
            bjPak pak = new bjPak();
            string[]files = Directory.GetFiles(@"C:\out\");

            try
            {
                //Add all files in the folder
                pak.AddFiles(files);
                //Place the pack file in the folder.
                //Ps make sure the file is created first as I nt added createing folders as yet
                pak.CreatePack(@"C:\out\bak\backup.pak");
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        private void cmdUnpack_Click(object sender, EventArgs e)
        {
            string sPakFile = @"c:\out\bak\backup.pak";
            string sOutput = @"C:\backup\";

            bjPak pak = new bjPak();

            try
            {
                //Open pack file
                pak.OpenPack(sPakFile);
                //Write each file in the pack to the backup folder
                for (int x = 0; x < pak.FileCount; x++)
                {
                    File.WriteAllBytes(sOutput + pak.GetFile(x).Filename,
                        pak.GetFile(x).data);
                }
                pak.ClearFiles();
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }
    }
}