How can I generate random alphanumeric strings? [c

Question

How can I generate random 8 character alphanumeric strings in C#?

Answer 1

Another option could be to use Linq and aggregate random chars into a stringbuilder.

var chars = "abcdefghijklmnopqrstuvwxyz123456789".ToArray();
string pw = Enumerable.Range(0, passwordLength)
                      .Aggregate(
                          new StringBuilder(),
                          (sb, n) => sb.Append((chars[random.Next(chars.Length)])),
                          sb => sb.ToString());

Answer 2

A solution without using Random :

var chars = Enumerable.Repeat("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789", 8);

var randomStr = new string(chars.SelectMany(str => str)
                                .OrderBy(c => Guid.NewGuid())
                                .Take(8).ToArray());

Answer 3

I know this one is not the best way. But you can try this.

string str = Path.GetRandomFileName(); //This method returns a random file name of 11 characters
str = str.Replace(".","");
Console.WriteLine("Random string: " + str);

Answer 4

I don't know how cryptographically sound this is, but it's more readable and concise than the more intricate solutions by far (imo), and it should be more "random" than System.Random-based solutions.

return alphabet
    .OrderBy(c => Guid.NewGuid())
    .Take(strLength)
    .Aggregate(
        new StringBuilder(),
        (builder, c) => builder.Append(c))
    .ToString();

I can't decide if I think this version or the next one is "prettier", but they give the exact same results:

return new string(alphabet
    .OrderBy(o => Guid.NewGuid())
    .Take(strLength)
    .ToArray());

Granted, it isn't optimized for speed, so if it's mission critical to generate millions of random strings every second, try another one!

NOTE: This solution doesn't allow for repetitions of symbols in the alphabet, and the alphabet MUST be of equal or greater size than the output string, making this approach less desirable in some circumstances, it all depends on your use-case.

Answer 5

Very simple solution. It uses ASCII values and just generates "random" characters in between them.

public static class UsernameTools
{
    public static string GenerateRandomUsername(int length = 10)
    {
        Random random = new Random();
        StringBuilder sbuilder = new StringBuilder();
        for (int x = 0; x < length; ++x)
        {
            sbuilder.Append((char)random.Next(33, 126));
        }
        return sbuilder.ToString();
    }

}

Answer 6

We also use custom string random but we implemented is as a string's helper so it provides some flexibility...

public static string Random(this string chars, int length = 8)
{
    var randomString = new StringBuilder();
    var random = new Random();

    for (int i = 0; i < length; i++)
        randomString.Append(chars[random.Next(chars.Length)]);

    return randomString.ToString();
}

Usage

var random = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".Random();

or

var random = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789".Random(16);