/// <summary>
 /// This function price range button click operation.
 /// This function is used to filter operation.
 /// </summary>
 /// <returns> This function does not return a value  </returns>
 private void btnPriceRange_Click(object sender, EventArgs e)
 {
     flpMusicCdList.Controls.Clear();
     if (txtMinPrice.Text == "" || txtMaxPrice.Text == "")
     {
         MessageBox.Show("Please fill in the blanks. (min - max)", "Information", MessageBoxButtons.OK, MessageBoxIcon.Information);
         MusicCdScreen_Load(sender, e);
         txtMaxPrice.Text = "";
         txtMinPrice.Text = "";
     }
     else
     {
         foreach (Product product in StoreMainScreen.productList)
         {
             if (product is MusicCD)
             {
                 if (product.Price >= Int32.Parse(txtMinPrice.Text) && product.Price <= Int32.Parse(txtMaxPrice.Text))
                 {
                     MusicCdDesign musicCdScreen = new MusicCdDesign((MusicCD)product);
                     musicCdDesignsList.Add(musicCdScreen);
                     flpMusicCdList.Controls.Add(musicCdScreen);
                 }
             }
         }
     }
     if (flpMusicCdList.Controls.Count == 0)
     {
         MessageBox.Show("There is no product in the range you are looking for.", "Information", MessageBoxButtons.OK, MessageBoxIcon.Information);
         MusicCdScreen_Load(sender, e);
         txtMinPrice.Text = "";
         txtMaxPrice.Text = "";
     }
 }
 /// <summary>
 /// This function used to add musicCdDesign list and controls.
 /// </summary>
 /// <returns> This function does not return a value </returns>
 private void MusicCdScreen_Load(object sender, EventArgs e)
 {
     foreach (Product product in StoreMainScreen.productList)
     {
         if (product is MusicCD)
         {
             MusicCdDesign musicCdDesign = new MusicCdDesign((MusicCD)product);
             musicCdDesignsList.Add(musicCdDesign);
             flpMusicCdList.Controls.Add(musicCdDesign);
         }
     }
 }
 /// <summary>
 /// This function used to clear and add for musicCdDesign list and controls.
 /// </summary>
 /// <returns> This function does not return a value </returns>
 private void flpMusicCdList_VisibleChanged(object sender, EventArgs e)
 {
     txtSearch.Text = "Search here";
     if (musicCdDesignsList.Count > 0)
     {
         musicCdDesignsList.Clear();
         flpMusicCdList.Controls.Clear();
     }
     foreach (Product product in StoreMainScreen.productList)
     {
         if (product is MusicCD)
         {
             MusicCdDesign musicCdDesign = new MusicCdDesign((MusicCD)product);
             musicCdDesignsList.Add(musicCdDesign);
             flpMusicCdList.Controls.Add(musicCdDesign);
         }
     }
 }
 /// <summary>
 /// This function used to search product.
 /// </summary>
 /// <returns> This function does not return a value </returns>
 private void txtSearch_TextChanged(object sender, EventArgs e)
 {
     flpMusicCdList.Controls.Clear();
     if (txtSearch.Text == "")
     {
         MusicCdScreen_Load(sender, e);
     }
     else
     {
         foreach (Product product in StoreMainScreen.productList)
         {
             if (product is MusicCD)
             {
                 if (product.Name.ToUpper().Contains(txtSearch.Text.ToUpper()) || product.Name.ToLower().Contains(txtSearch.Text.ToLower()))
                 {
                     MusicCdDesign musicCdDesign = new MusicCdDesign((MusicCD)product);
                     musicCdDesignsList.Add(musicCdDesign);
                     flpMusicCdList.Controls.Add(musicCdDesign);
                 }
             }
         }
     }
 }