Generating a random decimal in C#

Question

How can I get a random System.Decimal? System.Random doesn't support it directly.

Answer 1

This is similar to Daniel's version, but will give the complete range. It also introduces a new extension method to get a random "any integer" value, which I think is handy.

Note that the distribution of decimals here is not uniform.

/// <summary>
/// Returns an Int32 with a random value across the entire range of
/// possible values.
/// </summary>
public static int NextInt32(this Random rng)
{
     int firstBits = rng.Next(0, 1 << 4) << 28;
     int lastBits = rng.Next(0, 1 << 28);
     return firstBits | lastBits;
}

public static decimal NextDecimal(this Random rng)
{
     byte scale = (byte) rng.Next(29);
     bool sign = rng.Next(2) == 1;
     return new decimal(rng.NextInt32(), 
                        rng.NextInt32(),
                        rng.NextInt32(),
                        sign,
                        scale);
}