162 words (approximately 1 min)

Overview

Pseudo-random number generator.

Thread Safety

Warning: System.Random is not thread safe.

For concurrent operations across multiple threads, use Random’s Shared property which returns a thread-safe Random instance.

Seeds

In .NET Core, System.Random’s default parameterless constructor uses a seed value produced by the thread-static random number generator itself. It also has a constructor overload that accepts an int as a seed.

Use

var bytes = new byte[5];
rand.NextBytes(bytes); // 5 random byte values.

rand.Next(); // Random integer.
rand.Next(101); // Random integer >= 0 and <= 100.
rand.Next(50, 101); // Random integer >= 50 and <= 100.

rand.NextSingle(); // Random floating point >= 0.0 and < 1.0.

rand.NextDouble(); // Random double > 0 and < 1.
rand.NextDouble(); // Random double > 0 and < 5.

rand.NextInt64(); // Non-negative random integer.
rand.NextInt64(101); // Non-negative random integer >= 0 and <= 100.
rand.NextInt64(50, 101); // Non-negative random integer >= 50 and <= 100.

rand.Sample(); // Random floating point number between 0.0 and 1.0.