All the patterns:

The patterns for DateTime.ToString ( ‘d’ ) :

The patterns for DateTime.ToString ( ‘D’ ) :

The patterns for DateTime.ToString ( ‘f’ ) :

The patterns for DateTime.ToString ( ‘F’ ) :

The patterns for DateTime.ToString ( ‘g’ ) :

The patterns for DateTime.ToString ( ‘G’ ) :

The patterns for DateTime.ToString ( ‘m’ ) :

The patterns for DateTime.ToString ( ‘r’ ) :

The patterns for DateTime.ToString ( ‘s’ ) :

The patterns for DateTime.ToString ( ‘u’ ) :

The patterns for DateTime.ToString ( ‘U’ ) :

The patterns for DateTime.ToString ( ‘y’ ) :

Building a custom DateTime.ToString Patterns

The following details the meaning of each pattern character. Note the K and z character.

||\c || Represents the escape character, and displays the character “c” as a literal when that character is preceded by the escape character (\). To insert the backslash character itself in the result string, the application should use two escape characters (“\\”).

Any other character copies any other character to the result string, without affecting formatting. ||

using System.Globalization;
using System.Threading;

//...
protected void Application_BeginRequest(Object sender, EventArgs e)
{    
  CultureInfo newCulture = (CultureInfo) System.Threading.Thread.CurrentThread.CurrentCulture.Clone();
  newCulture.DateTimeFormat.ShortDatePattern = "dd-MMM-yyyy";
  newCulture.DateTimeFormat.DateSeparator = "-";
  Thread.CurrentThread.CurrentCulture = newCulture;
}

It does this by making the class constructor private so that it [the singleton itself] has full control over when the class instance is created.  In order to gain access to an instance of a class that implements the Singleton pattern, the developer must call a shared/static method of that Singleton class.

A VB example of a Singleton

A C# example of a Singleton

With the Singleton Design Pattern in place, the developer can easily access that single object instance without needing to worry about inadvertently creating multiple instances, and provides a global point of access to it.

VB – Dim mySingleton As SingletonSample = SingletonSample.Instance

C# – SingletonSample mySingleton = SingletonSample.Instance();

<?xml version="1.0"?> 
<configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0"> 
  ...etc... 
  <system.web> 
    <authentication mode="Windows" /> 
    <authorization> 
      <allow roles="MYDOMAIN\MyAppUsers" /> 
      <deny users="*" /> 
    </authorization> 
  </system.web> 
</configuration>

Then you want to make a landing page for users who aren’t allowed to log in. This is just a plain HTML page, you can call it ‘noaccess.htm’. Now you want to make it send disallowed people to this ‘noaccess.htm’. Open or create the Global.asax page, and change/add this function:

// This redirects people without access to the noaccess.htm page 
protected void Application_EndRequest(Object sender, EventArgs e) 
{ 
  HttpContext context = HttpContext.Current; 
  if (context.Response.Status.Substring(0, 3).Equals("401")) 
  { 
    context.Response.ClearContent(); 
    context.Response.Write("<scr" + 
      "ipt language=javascript> self.location='noaccess.htm'; </sc" + 
      "ript>"); 
  } 
}

How to figure out who is logged in Quite simple this one – it is stored in this variable, accessible from your aspx.cs code-behind classes (Update – FIXED):

HttpContext.Current.Request.ServerVariables["AUTH_USER"];

Say you’ve got a literal control on your webform, and you want to show the currently logged on user, you could do this:

literalLoggedOnUser.Text = HttpContext.Current.Request.ServerVariables["AUTH_USER"];

How to give different permissions to different users Say you want to give some people more access than others, you’ll want to create another AD group for these users: “MYDOMAIN\MyAppAdmins”. Open up your web.config and add the appSettings section like so:

<?xml version="1.0"?> 
<configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0"> 
  <appSettings> 
    <add key="AdminGroup" value="MYDOMAIN\MyAppAdmins"/> 
  </appSettings> 
  ...etc... 
</configuration>

The reason for adding the name of the admin group in the web.config is so that if you have different AD groups for the development vs production environments, it’ll be a simple matter of only changing the web.config. The principle adhered to here is that the only difference between development and production should be the web.config file. Then you’ll use this piece of code to check if the current user is in that group:

string group = ConfigurationManager.AppSettings["AdminGroup"]; 
if (User.IsInRole(group)) 
{ 
  // this user is an administrator 
} 
else 
{ 
  // this user is a common pleb 
}

Hint: You’re most likely to place code like that in the Page_Load function for the admin pages. Notes This is for C# ASP.Net 2. Some things may be different with VB.Net or .Net 1.1 Redirect to noaccess.htm:

credit: http://www.splinter.com.au/easy-integrated-active-directory-security-in/