C# - Generate a unique 6-digit Random code

Question

I wrote below class to gereate a unique 6-digit Random code in database:

public class RndCode
{
    public static string Generate(int ID, int Length = 5)
    {
        string allowedChars = "0123456789";
        char[] chars = new char[Length];
        string code = "";
        Random rd = new Random();

        for (int i = 0; i < Length; i++)
        {
           chars[i] = allowedChars[rd.Next(0, allowedChars.Length)];
        }

        string VCode = new string(chars);
        using (DataBaseContext db = new DataBaseContext())
        {
            if (!db.Members.Any(o => o.ID == ID && o.Code == VCode))
            {
                code = VCode;
            }
            else
            {
                Generate(ID, Length);
            }
        }
        return code;
     }
 }

and use it in my controller:

int id = 250;
List<string> AllCodes = new List<string>();
for (int i = 0; i < 20 ; i++)
{
     var RandomCode = Service.RndCode.Generate(id, 6);

     AllCodes.Add(RandomCode);
}

but AllCodes contains more repetitious numbers. why?

What is wrong?

Your recursive call to yourself is also broken because you don't do anything with the result of the recursive call, instead returning `code` which will still just be `""`, if you're lucky and don't cause a stack overflow. And you're only checking codes in the DB - you're not checking codes *you're just generated yourself* in a previous iteration. — Damien_The_Unbeliever, Jan 21 '19 at 07:57

C# - Generate a unique 6-digit Random code

0 Answers0