C# Random Password Generator

Question

Here is the code: (passwordLengthBox is a NumericUpDown Box, r and k are random numbers)

    private void generateButton_Click(object sender, EventArgs e)
            {
                int r, k;
                int passwordLength = (Int32)passwordLengthBox.Value;
                string password = "";
                char[] upperCase = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z' };
                char[] lowerCase = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z' };
                int[] numbers = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };
                Random rRandom = new Random();



                for (int i = 0; i < passwordLength; i++)
                {
                    r = rRandom.Next(3);

                    if (r == 0)
                    {
                        k = rRandom.Next(0, 25);
                        password += upperCase[k];
                    }

                    else if (r == 1)
                    {
                        k = rRandom.Next(0, 25);
                        password += lowerCase[k];
                    }

                    else if (r == 2)
                    {
                        k = rRandom.Next(0, 9);
                        password += numbers[k];
                    }

                }

                textBox.Text = password;
            }

What this program does is to create a random password with letters (both upper case and lower case) and numbers at the length that I choose. The problem is that the program does not make the password length as I chose.

For example: if I type 5 in the NumericUpDown Box (passwordLengthBox) that sets the Password Length sometimes its giving me passwords that are 5 chars long and sometime 6/7/8 chars long passwords.

What is my mistake?

Answer 1

Problem is here:

int[] numbers = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };

With that declaration every time a number is appended into password it is taken as ASCII number, not a real value. So you're adding integers from 48 to 57, what makes result string longer then expected.

e.g. when 6 is generated as a random number, you're appending something like: ((int)'6').ToString() into your password variable, what actually adds 54 instead of 6.

Declare that array as char[] and it will works fine.