Using Random in ASP.NET

In C# and ASP.NET you can generate random numbers like this:

Random r = new Random(System.DateTime.Now.Millisecond);

double d = r.NextDouble();

But, in an stateless ASP.NET world, you will get the same random number generator starting over at it’s pseudo-random beginning each time the page posts back and you create a new Random object. To keep a random number generator moving forward with new random numbers, use something like:

public static double roll() {

Random r;

if (HttpContext.Current.Session["r"] == null)

{

r = new Random(System.DateTime.Now.Millisecond);

HttpContext.Current.Session["r"] = r;

}

else

{

r = (Random)HttpContext.Current.Session["r"];

}

return r.NextDouble();

}