Best way to randomize an array with .NET

Question

What is the best way to randomize an array of strings with .NET? My array contains about 500 strings and I\'d like to create a new Array with the same strings b

Answer 1

If you're on .NET 3.5, you can use the following IEnumerable coolness:

Random rnd=new Random();
string[] MyRandomArray = MyArray.OrderBy(x => rnd.Next()).ToArray();    

Edit: and here's the corresponding VB.NET code:

Dim rnd As New System.Random
Dim MyRandomArray = MyArray.OrderBy(Function() rnd.Next()).ToArray()

Second edit, in response to remarks that System.Random "isn't threadsafe" and "only suitable for toy apps" due to returning a time-based sequence: as used in my example, Random() is perfectly thread-safe, unless you're allowing the routine in which you randomize the array to be re-entered, in which case you'll need something like lock (MyRandomArray) anyway in order not to corrupt your data, which will protect rnd as well.

Also, it should be well-understood that System.Random as a source of entropy isn't very strong. As noted in the MSDN documentation, you should use something derived from System.Security.Cryptography.RandomNumberGenerator if you're doing anything security-related. For example:

using System.Security.Cryptography;

...

RNGCryptoServiceProvider rnd = new RNGCryptoServiceProvider();
string[] MyRandomArray = MyArray.OrderBy(x => GetNextInt32(rnd)).ToArray();

...

static int GetNextInt32(RNGCryptoServiceProvider rnd)
    {
        byte[] randomInt = new byte[4];
        rnd.GetBytes(randomInt);
        return Convert.ToInt32(randomInt[0]);
    }