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POExplanation of how this code works (C#)
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  1. POExplanation of how this code works (C#)
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    copied!<p>Can anyone explain me the following code:</p> <pre><code>using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Windows.Forms; using System.Drawing; namespace web.frmcolor { public class FormEx : Form { /// &lt;summary&gt; /// Set the default color for the designer /// &lt;/summary&gt; static FormEx() { _globalBackgroundColor = default(Color?); } private static void InvalidateForms() { try { for (int i1 = 0; i1 &lt; Application.OpenForms.Count; i1++) { try { FormEx frm = (Application.OpenForms[i1] as FormEx); if (frm != null) { frm.Invalidate(true); frm.Refresh(); } } catch { //Should never happen } } } catch { //this will catch if the form count changes } } private static Color? _globalBackgroundColor; /// &lt;summary&gt; /// Sets the background color for all forms /// &lt;/summary&gt; public static Color? GlobalBackgroundColor { get { return FormEx._globalBackgroundColor; } set { if (FormEx._globalBackgroundColor != value) { FormEx._globalBackgroundColor = value; InvalidateForms(); } } } public override Color BackColor { get { return (_globalBackgroundColor == null ? base.BackColor : (Color)_globalBackgroundColor); } set { base.BackColor = value; } } /// &lt;summary&gt; /// Create a new colored form /// &lt;/summary&gt; public FormEx() : base() { } private void InitializeComponent() { this.SuspendLayout(); // // FormEx // this.ClientSize = new System.Drawing.Size(292, 266); this.Name = "FormEx"; this.Load += new System.EventHandler(this.FormEx_Load); this.ResumeLayout(false); } private void FormEx_Load(object sender, EventArgs e) { } } } </code></pre> <p>Since I am a beginner I am not able to understand how the above coding works. I found this coding while browsing through internet.</p> <p>The part I don't understand is this:</p> <pre><code>_globalBackgroundColor = default(Color?); </code></pre> <p>Why there is a <code>?</code> after the color, what does that indicate?</p>
 

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