Question

I’m trying to generate a random Product list using the following method, but I’m getting the same Product instance multiple times.

Output for count 5:
Name: Qmlcloboa Price: 3.608848
Name: Qmlcloboa Price: 3.608848
Name: Qmlcloboa Price: 3.608848
Name: Qmlcloboa Price: 3.608848
Name: Qmlcloboa Price: 3.608848

I read on List type being a reference type & it overwrites stuff. Below is my code. am I missing something which could give me unique Product instances? Thanks & I would appreciate your help.

public List<Product> ProductGroupGenerator(int count)
    {
        List<Product> pList = new List<Product>();

        for (int i = 0; i < count; i++)
        {
            Random r = new Random();
            string alphabet = "abcdefghijklmnopqrstuvwyxzeeeiouea";
            Func<char> randomLetter = () => alphabet[r.Next(alphabet.Length)];
            Func<int, string> makeName =
              (length) => new string(Enumerable.Range(0, length)
                 .Select(x => x == 0 ? char.ToUpper(randomLetter()) : randomLetter())
                 .ToArray());

            //string last = makeName(r.Next(7) + 7);
            //string company = makeName(r.Next(7) + 7) + " Inc.";

            string prodName = makeName(r.Next(5) + 5);
            int unitsInStock = r.Next(100);
            float unitPrice = (float)(r.NextDouble() * 10);

            Product p = new Product();
            p.Name = prodName;
            p.UnitsInStock = unitsInStock;
            p.UnitPrice = unitPrice;

            pList.Add(p);

            p = null;
        }

        return pList;
    }

Answer 1

When invoked too quickly, multiple Random r = new Random()‘s will produce Randoms with identical seeds.

Declare it once outside the for loop and you should have better values.

    Random r = new Random();
    for (int i = 0; i < count; i++)
    {