One of the benefits that C# and the .NET framework give to developers is the metadata contained within the assemblies.This metadata contains all information about the assembly which is not specific instructions.This method allows developers easily embed resource "files" into the assembly,and access these resources at runtime through reflection.This is incredibly useful for embedding things such as help files, bitmaps, and windows metafiles.The key advantage to this system,is that these "files" are then carried within the executable file.You don't have to worry about a user accidently deleting or modifying the file, and thus breaking your code.This does,however,cause a signifigant increase to the size of your executable.As such,huge bitmaps or video files are probably not the best choices to use as embedded resources.In this tutorial,we will be showing how to embed bitmaps into the assembly's metadata,and then attach a stream to that resource in order to open it as a bitmap.We will be creating a program which loads all bitmaps which are embedded resources, and display a randomly chosen one when the user clicks a button.To begin,we open VS.NET and create a new C# Windows Application.The next step is to add the files you want as a resource to the project.To do this you right click on the project name,and select "Add Existing Items."This will bring up a dialog where you can select the files to add. This will cause VS.NET to copy the file into your project's directory if it is not already there.This file is now part of the project you previously created.

Now lets modify our code so as to load the bitmaps into an ArrayList.

private void Form1_Load(object sender,System.EventArgs e)
{
   Stream imgStream = null;
   Bitmap bmp = null;
   Assembly a = Assembly.GetExecutingAssembly()
   string [] resNames = a.GetManifestResourceNames();
   txtInfo.Clear();
   txtInfo.Text += String.Format
                        ("Found {0} resources\r\n",resNames.Length);
   txtInfo.Text += "----------\r\n";
   foreach(string s in resNames)
   {
      txtInfo.Text += s + "\r\n";
      if(s.EndsWith(".bmp"))
      {
         imgStream = a.GetManifestResourceStream(s);
         if( !(null==imgStream) )
         {
               bmp = Bitmap.FromStream( imgStream ) as Bitmap;
               if( !(null==bmp) )
               {
                     pics.Add( bmp );
               }
               bmp = null;
               imgStream.Close();
               imgStream = null;
         }
      }
   }
   txtInfo.Text += "----------\r\n";
   txtInfo.Text += String.Format("Found {0} Bitmaps\r\n",
   pics.Count);
}

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Reflection;
using System.IO;
using System.Diagnostics;
namespace ResourceDemo
{
        /// <summary>
        /// Summary description for Form1.
        /// </summary>
        public class Form1 : System.Windows.Forms.Form
        {
            ArrayList pics;
            private System.Windows.Forms.GroupBox groupBox1;
            private System.Windows.Forms.PictureBox pBox;
            private System.Windows.Forms.Button btnDisplay;
            private System.Windows.Forms.TextBox txtInfo
            private System.ComponentModel.Container components = null;
            public Form1()
            {
                InitializeComponent();
                pics = new ArrayList();
            }
            protected override void Dispose( bool disposing )
            {
                if( disposing )
                {
                        if (components != null)
                        {
                                components.Dispose();
                        }
                }
                base.Dispose( disposing );
            }
            #region Windows Form Designer generated code
            private void InitializeComponent()
            {
                this.pBox = new System.Windows.Forms.PictureBox();
                this.groupBox1 = new System.Windows.Forms.GroupBox();
                this.btnDisplay = new System.Windows.Forms.Button();
                this.txtInfo = new System.Windows.Forms.TextBox();
                this.groupBox1.SuspendLayout();
                this.SuspendLayout();
                this.pBox.BorderStyle=System.Windows.Forms.BorderStyle.FixedSingle;
                this.pBox.Location = new System.Drawing.Point(8, 8);
                this.pBox.Name = "pBox";
                this.pBox.Size = new System.Drawing.Size(264, 272);
                this.pBox.TabIndex = 0;
                this.pBox.TabStop = false;
                this.pBox.SizeMode=System.Windows.Forms.PictureBoxSizeMode
                .StretchImage;
                this.groupBox1.Controls.AddRange(new
                System.Windows.Forms.Control[] {
                                                                    this.txtInfo,
                                                                    this.btnDisplay});
                this.groupBox1.Location = new System.Drawing.Point(288, 8);
                this.groupBox1.Name = "groupBox1";
                this.groupBox1.Size = new System.Drawing.Size(192, 264);
                this.groupBox1.TabIndex = 1;
                this.groupBox1.TabStop = false;
                this.btnDisplay.Location = new System.Drawing.Point(48, 24);
                this.btnDisplay.Name = "btnDisplay";
                this.btnDisplay.Size = new System.Drawing.Size(96, 23);
                this.btnDisplay.TabIndex = 0;
                this.btnDisplay.Text = "Display Picture";
                this.btnDisplay.Click += new System.EventHandler(this.button1_Click);
                this.txtInfo.Location = new System.Drawing.Point(8, 56);
                this.txtInfo.Multiline = true;
                this.txtInfo.Name = "txtInfo";
                 this.txtInfo.ReadOnly = true;
                this.txtInfo.Size = new System.Drawing.Size(176, 200);
                this.txtInfo.TabIndex = 2;
                 this.txtInfo.Text = "txtInfo";
                this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
                this.ClientSize = new System.Drawing.Size(496, 293);
                this.Controls.AddRange(new System.Windows.Forms.Control[] {
                                                    this.groupBox1,
                                                    this.pBox});
               this.Name = "Form1";
               this.Text = "Form1";
               this.Load += new System.EventHandler(this.Form1_Load);
               this.groupBox1.ResumeLayout(false);
               this.ResumeLayout(false);
         }
        #endregion
       [STAThread]
       static void Main()
       {
              Application.Run(new Form1());
       }
       private void button1_Click(object sender, System.EventArgs e)
       {
              generator = new Random();
              Bitmap bmp = pics[ generator.Next(pics.Count) ] as Bitmap;
              if(!(null==bmp))
              {
                     pBox.Image = bmp;
              }
              bmp = null;
              generator = null;
        }
       private void Form1_Load(object sender, System.EventArgs e)
       {
              Stream imgStream = null;
              Bitmap bmp = null;
              // get a reference to the current assembly
              Assembly a = Assembly.GetExecutingAssembly();
              // get a list of resource names from the manifest
              string [] resNames = a.GetManifestResourceNames();
              // populate the textbox with information about our resources
              // also look for images and put them in our arraylist
              txtInfo.Clear();
              txtInfo.Text += String.Format("Found {0} resources\r\n", resNames.Length);
              txtInfo.Text += "----------\r\n";
              foreach(string s in resNames)
              {
                     txtInfo.Text += s + "\r\n";
                     if(s.EndsWith(".bmp"))
                     {
                            // attach to stream to the resource in the manifest
                            imgStream = a.GetManifestResourceStream(s);
                            if( !(null==imgStream) )
                            {
                                   // create a new bitmap from this stream and
                                   // add it to the arraylist
                                   bmp = Bitmap.FromStream( imgStream ) as Bitmap;
                                   if( !(null==bmp) )
                                   {
                                          pics.Add( bmp );
                                   }
                                   bmp = null;
                                   imgStream.Close();
                                   imgStream = null;
                            }
                     }
              }
              txtInfo.Text += "----------\r\n";
              txtInfo.Text += String.Format("Found {0} Bitmaps\r\n",
                                                             pics.Count);
       }
    }
}