Generate a Random Floating Point Number between two Numbers

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The Random.NextDouble() method returns a random number between 0.0 and 1.0. However what if you want to specify the upper and lower limits and then generate a random double number? Here’s some code I had written a couple of months ago to generate a random double number between two numbers:

C#

class Program
{
    static void Main(string[] args)
    {
        double dr = GenRand(1.0, 20.0);
        Console.WriteLine(dr);
        Console.ReadLine();
    }

    static double GenRand(double one, double two)
    {
        Random rand = new Random();
        return one + rand.NextDouble() * (two - one);
    }
}

VB.NET

Friend Class Program
 Sub Main(ByVal args() As String)
     Dim dr As Double = GenRand(1.0, 20.0)
     Console.WriteLine(dr)
     Console.ReadLine()
 End Sub

Shared Function GenRand(ByVal one As Double, ByVal two As Double) As Double
     Dim rand As New Random()
     Return one + rand.NextDouble() * (two - one)
End Function
End Class

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About The Author

Suprotim Agarwal, Developer Technologies MVP (Microsoft Most Valuable Professional) is the founder and contributor for DevCurry, DotNetCurry and SQLServerCurry. He is the Chief Editor of a Developer Magazine called DNC Magazine. He has also authored two Books - 51 Recipes using jQuery with ASP.NET Controls. and The Absolutely Awesome jQuery CookBook.

Follow him on twitter @suprotimagarwal.