password generator in c#

I want to create a random password generator in my ASP.NET C# web application.

I have created that but it 开发者_高级运维is applicable only for the integer format. If I give any characters it shows the debugging error as "my input format is wrong".

But i want to enter both string and integer. For example my textbox field may be

dft-001

I want a random password for this value and also my length should be restricted to 8 digits or characters only.

My current code:

public static string CreateRandomPassword(int PasswordLength)
    {

        string _allowedChars = "abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNOPQRSTUVWXYZ0123456789-";
        Random randNum = new Random();
        char[] chars = new char[PasswordLength];
        int allowedCharCount = _allowedChars.Length;

        for (int i = 0; i < PasswordLength; i++)
        {
            chars[i] = _allowedChars[(int)((_allowedChars.Length) * randNum.NextDouble())];
        }

        return new string(chars);
    }


protected void Button1_Click(object sender, EventArgs e)
    {
        userid.Text = "Your id is:     " + id.Text;
        if(id .Text!="")
        {

            string myInt = id.Text.ToString(); 
            password.Text = "Your password is: " + CreateRandomPassword(int.Parse(myInt)); 
        }
       }

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There are a few things you can do to correct this based on what you have stated in your requirements.

public static string CreateRandomPassword()  //If you are always going to want 8 characters then there is no need to pass a length argument
    {
        string _allowedChars = "abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNOPQRSTUVWXYZ0123456789-";
        Random randNum = new Random((int)DateTime.Now.Ticks);  //Don't forget to seed your random, or else it won't really be random
        char[] chars = new char[8];
        //again, no need to pass this a variable if you always want 8

        for (int i = 0; i < 8; i++)
        {
            chars[i] = _allowedChars[randNum.Next(_allowedChars.Length)];
            //No need to over complicate this, passing an integer value to Random.Next will "Return a nonnegative random number less than the specified maximum."
        }
        return new string(chars);
    }


protected void Button1_Click(object sender, EventArgs e)
    {
        userid.Text = "Your id is:     " + id.Text;
        if(id .Text!="")
        {
            password.Text = "Your password is: " + CreateRandomPassword(); 
        }
    }

If I've understood what you want to do correctly, then this should get you there.

Ref: MSDN Random.Next

---

Shouldn't it be:

password.Text = CreateRandomPassword(int.Prase(myInt))

However, it is extremely strange that you are:

1. Taking a user ID and converting it to string (I assume it is a number)
2. Parsing that string back to a number
3. Using this number as the length of your password

If your user ID is, say, 345678, you are creating a password which contains 345,678 characters! Please check your program logic.

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Check out the following link for password generator in asp.net

Password generator in ASP.NET

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Depending on how fast the function is called multiple times the passwords will look similar if you use Random as a local variable (even when using Ticks as seeds). A solution for that is to use it as a static variable to ensure the result is truly random.

private static Random rand = new Random();

Another one is to use .net built-in solutions like Path.GetRandomFileName() which will give you results like

// w143kxnu.idj

Use only the first 8 chars and arbitrary change some chars to Upper().

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Changing your Button_Click method to the following will give you a random password of 8 characters:

static const int PASSWORD_LENGTH = 8;
protected void Button1_Click(object sender, EventArgs e)
{
    userid.Text = "Your id is:     " + id.Text;
    if(id .Text!="")
    {

        string myInt = id.Text.ToString(); 
        password.Text = "Your password is: " + CreateRandomPassword(PASSWORD_LENGTH); 
    }
   }

Otherwise if id.Text contains any letters at all, it will fail which is most likely the error you are getting.

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There is 2 problems. First id.Text.ToString() may contain some characters that make it fail to be parsed to int. "helo123" can't be parsed directly into int. This causes "input format is wrong". You should only do this if you are sure the ID contains only numbers.

Second, CreateRandomPassword(int.Parse(myInt)) creates a password that is as long as the value of the id. You should CreateRandomPassword(10) or CreateRandomPassword(randNum.Next(5, 12)). If your ID is 500, your password would be 500 characters long and if your field is supposed to be 32 characters, this could fail with "input format is wrong".

---

First we take 6 (any) random numbers from “0123456789”.

Then we create a function that returns the random number.

private string GetRandomNumber()
{
    var chars = "0123456789";
    var random = new Random();
    var result = new string(
        Enumerable.Repeat(chars, 6)
                  .Select(s => s[random.Next(s.Length)])
                  .ToArray());
    return result;
}

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