Is the C# random number generator guaranteed to be stable?

Question

I am writing a program which uses a lot of random numbers to generate stuff. But I want to assure that when starting with the same seed the generated content is the same. So when I create my random number like this:

Random r = new Random(seed);
int num = r.Next(); 

How is it guaranteed that num is always the same over time (means: several releases of .NET)? Is there a standardized list in the background? Or should I use my own "random list" to be sure that this will never change?

Answer 1

No, the result from the same seed can vary across versions of the framework, and it's in the documentation here:

The implementation of the random number generator in the Random class isn't guaranteed to remain the same across major versions of the .NET Framework. As a result, you shouldn't assume that the same seed will result in the same pseudo-random sequence in different versions of the .NET Framework.

That documentation also contains variations of this advice in other sections, e.g. in Retrieve the same sequence of random values:

The following example uses 100100 as an arbitrary seed value to instantiate the Random object, displays 20 random floating-point values, and persists the seed value. It then restores the seed value, instantiates a new random number generator, and displays the same 20 random floating-point values. Note that the example may produce different sequences of random numbers if run on different versions of the .NET Framework.

And:

However, note that Random objects in processes running under different versions of the .NET Framework may return different series of random numbers even if they're instantiated with identical seed values.