Question

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Is this a good way to generate a string of random characters?
How can I generate random 8 character, alphanumeric strings in C#?

This is the code that I have so far.

    private void button1_Click(object sender, EventArgs e)
    {
        string rand1 = RandomString(5);
        string rand2 = RandomString(5);
        string rand3 = RandomString(5);
        string rand4 = RandomString(5);
        string rand5 = RandomString(5);
        textBox1.Text = rand1 + "-" + rand2 + "-" + rand3 + "-" + rand4 + "-" + rand5;

    }
    private static Random random = new Random((int)DateTime.Now.Ticks);
    private string RandomString(int Size)
    {
        StringBuilder builder = new StringBuilder();
        char ch;
        for (int i = 0; i < Size; i++)
        {
            ch = Convert.ToChar(Convert.ToInt32(Math.Floor(26 * random.NextDouble() + 65)));
            builder.Append(ch);
        }
        return builder.ToString();
    }

BUT it just creates a random string of 5 chars.
I want it to create a string of 5 chars and integers.
How would I do this? Thanks in advance!

Answer 1

Use an input array to draw your values from:

private static string RandomString(int length)
{
    const string pool = "abcdefghijklmnopqrstuvwxyz0123456789";
    var builder = new StringBuilder();

    for (var i = 0; i < length; i++)
    {
        var c = pool[random.Next(0, pool.Length)];
        builder.Append(c);
    }

    return builder.ToString();
}

Or the (inevitable) Linq solution:

private static string RandomString(int length)
{
    const string pool = "abcdefghijklmnopqrstuvwxyz0123456789";
    var chars = Enumerable.Range(0, length)
        .Select(x => pool[random.Next(0, pool.Length)]);
    return new string(chars.ToArray());
}