PROGRAMMING: C# CODE TO GENERATE RANDOM PASSWORDS DEVELOPER TUTORIAL

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C# CODE TO GENERATE RANDOM PASSWORDS - DEVELOPED BY JAY STILLA + CO. MISTERBOTS

Here is a very useful C# code snippet for generating random strong passwords. The password is generated using upper case and lower case alphabets, numerals and special characters.

//create constant strings for each type of characters

static string alphaCaps = "QWERTYUIOPASDFGHJKLZXCVBNM";

static string alphaLow = "qwertyuiopasdfghjklzxcvbnm";

static string numerics = "1234567890";

static string special = "@#$";

//create another string which is a concatenation of all above

string allChars = alphaCaps + alphaLow + numerics + special;

Random r = new Random();

public string GenerateStrongPassword(int length)

{

    String generatedPassword = "";

    if (length < 4)

        throw new Exception("Number of characters should be greater than 4.");

    // Generate four repeating random numbers are postions of

    // lower, upper, numeric and special characters

    // By filling these positions with corresponding characters,

    // we can ensure the password has atleast one

    // character of those types

    int pLower, pUpper, pNumber, pSpecial;

    string posArray = "0123456789";

    if (length < posArray.Length)

        posArray = posArray.Substring(0, length);

    pLower = getRandomPosition(ref posArray);

    pUpper = getRandomPosition(ref posArray);

    pNumber = getRandomPosition(ref posArray);

    pSpecial = getRandomPosition(ref posArray);

    for (int i = 0; i < length; i++)

    {

        if (i == pLower)

            generatedPassword += getRandomChar(alphaCaps);

        else if (i == pUpper)

            generatedPassword += getRandomChar(alphaLow);

        else if (i == pNumber)

            generatedPassword += getRandomChar(numerics);

        else if (i == pSpecial)

            generatedPassword += getRandomChar(special);

        else

            generatedPassword += getRandomChar(allChars);

    }

    return generatedPassword;

}

private string getRandomChar(string fullString)

{

    return fullString.ToCharArray()[(int)Math.Floor(r.NextDouble() * fullString.Length)].ToString();

}

private int getRandomPosition(ref string posArray)

{

    int pos;

    string randomChar = posArray.ToCharArray()[(int)Math.Floor(r.NextDouble()

                                   * posArray.Length)].ToString();

    pos = int.Parse(randomChar);

    posArray = posArray.Replace(randomChar, "");

    return pos;

}