Random Number Generator Use - C#

Problem

Generate random numbers efficiently. Although your algorithm cannot be truly random, it must appear so for any human being observing it. You may want to use this in a simple game or in rotating content. Examine random numbers in object-oriented programs.

Solution: C#

I will spare you the theoretical aspect of random numbers. Instead, let's look at the C# random number generator. Microsoft provides some useful resources, and it says the following things about these methods.

• Uses a seed value
  "The random number generation starts from a seed value. If the same seed is used repeatedly, the same series of numbers is generated."
• How to improve randomness
  "One way to produce different sequences is to make the seed value time-dependent."
  (This means that if the time is the same when two randoms are created, you have a problem.)
• ... and be fast
  "To improve performance, create one Random to generate many random numbers over time."

How can I code it?

You can put the Random object in a new class, and then just use that class when you want to make a new random number. The examples at Microsoft use parameters, but this is more object-oriented and easy.

using System;

class RandomNum
{
    /// <summary>
    /// The random object. It is automatically initialized with a time
    /// seed. If you only create one object at a time, this is sufficient.
    /// </summary>
    Random _random = new Random();

    /// <summary>
    /// Wrapper method to return the next random number in our
    /// sequence. It is more efficient and more 'random' to
    /// store only one Random object and reuse it.
    /// </summary>
    public int GetRandom()
    {
        return _random.Next();
    }
}

• New class declared
  The above code can be placed in a file and it is a class. Look at how the Random object is created. It uses its default constructor, which uses a time seed.
• GetRandom() method exposed
  This method is what we will call from outside the class. It will operate on the private member _random.
• Other notes
  The comments are XML comments, which Visual Studio can use in its UI. Also the underscore prefixes the member variable, which is a standard syntax for clarity.

Why do I need to use the class?

You don't always. You can store the Random object locally in a method and directly use it. The example shows how you can use it in the internal part of a class. If you have a class that needs to return a random set of objects, it should store a Random object itself.

Classes should store Random

In object-oriented programming, classes are like "machines", and they should store and manage the Random number generator internally. In the RandomNum example, think of a machine that needs a random number for its output (such as in a simulation).

Conclusion

Use the series of numbers returned by Random.Next() for a pseudo-random number generator. Reuse the same Random generator over the course of your program for best randomness. Store a Random object locally in classes as a member for best performance and good design.