Since this method simply determines if any child controls exist, it can enhance performance by allowing you to avoid an unnecessary Count property call. Calls to this property require a ControlCollection object to be instantiated. If there are no children, this object creation wastes server resources.

The HasControls method should be overridden only to change metadata attributes such as EditorBrowsableAttribute. For more information about using attributes, see Extending Metadata Using Attributes.

The following example uses the HasControls method to determine if any controls exist before using the Count property to iterate through a ControlCollection object.

If HasControls() Then
    Dim i As Integer
    For i = 0 To Controls.Count - 1
        Controls(i).RenderControl(writer)
    Next i
End If

if (HasControls()) {
                 for (int i=0; i < Controls.Count; i++) {
                     Controls[i].RenderControl(writer);
                 }
   }

.NET Framework

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference