Keith Rull - Generating random strings and numbers in C# and VB.NET

Generating random strings and numbers in C# and VB.NET

Last night i decided to create a basic example on how to use the Random class in the .NET framework since randomization can also be useful in doing programs specially when designing applications that requires unique keys. One example of a program that requires a unique key is a random password generator.

I will not dive into details on how to create a random password generator, but we will take a closer look on how the Random class in .NET works.

As i have said awhile ago, i just show a basic example, not the complicated algorithm bloated with arrays and pointers.

Heres the C# sample:

using System;
using System.Text;

class RandomStringsAndNumbersCS
{
    /// <summary>
    /// The main entry point for the application.
    /// </summary>
    [STAThread]
    static void Main(string[] args)
    {
         //Generate a random number between 1000 and 9999.
         int intRandomNumber = GenerateRandomInteger(1000, 9999);
         //Generate a random string with the size of 16
         string strRandomString = GenerateRandomString(16);
         //print the result to the screen
         Console.WriteLine("Random Number:" + intRandomNumber.ToString());
         Console.WriteLine("Random String:" + strRandomString);
         //Pause to view the result.
         Console.ReadLine();
    }

    private static int GenerateRandomInteger(int intMin, int intMax)
    {
        //Create a new instance of the class Random
        Random randomNumber = new Random();
        //Generate a random number using intMin as the minimum and intMax as the maximum
        return randomNumber.Next(intMin, intMax);
    }

    private static string GenerateRandomString(int intLenghtOfString)
    {
        //Create a new StrinBuilder that would hold the random string.
        StringBuilder randomString = new StringBuilder();
        //Create a new instance of the class Random
        Random randomNumber = new Random();
        //Create a variable to hold the generated charater.
        Char appendedChar;
        //Create a loop that would iterate from 0 to the specified value of intLenghtOfString
        for(int i= 0; i<= intLenghtOfString; ++i)
        {
            //Generate the char and assign it to appendedChar
            appendedChar = Convert.ToChar(Convert.ToInt32(26 * randomNumber.NextDouble()) + 65);
            //Append appendedChar to randomString
            randomString.Append(appendedChar);
        }
        //Convert randomString to String and return the result.
        return randomString.ToString();
    }
}

And here's the VB.NET sample:

Imports System.Text

Module RandomStringsAndNumbersVB

   Sub Main()
      'Generate a random number between 1000 and 9999.
      Dim intRandomNumber As Integer = GenerateRandomInteger(1000, 9999)
      'Generate a random string with the size of 16
      Dim strRandomString As String = GenerateRandomString(16)
      'print the result to the screen
      Console.WriteLine("Random Number:" & intRandomNumber.ToString())
      Console.WriteLine("Random String:" & strRandomString)
      'Pause to view the result.
      Console.ReadLine()
    End Sub

   Private Function GenerateRandomInteger(ByVal intMin As Integer, ByVal intMax As Integer) As Integer
      'Create a new instance of the class Random
      Dim randomNumber As Random = New Random
      'Generate a random number using intMin as the minimum and intMax as the maximum
      Return randomNumber.Next(intMin, intMax)
   End Function

   Private Function GenerateRandomString(ByVal intLenghtOfString As Integer) As String
      'Create a new StrinBuilder that would hold the random string.
      Dim randomString As StringBuilder = New StringBuilder
      'Create a new instance of the class Random
      Dim randomNumber As Random = New Random
      'Create a variable to hold the generated charater.
      Dim appendedChar As Char
      'Create a loop that would iterate from 0 to the specified value of intLenghtOfString
      For i As Integer = 0 To intLenghtOfString
         'Generate the char and assign it to appendedChar
         appendedChar = Convert.ToChar(Convert.ToInt32(26 * randomNumber.NextDouble()) + 65)
         'Append appendedChar to randomString
         randomString.Append(appendedChar)
      Next
      'Convert randomString to String and return the result.
      Return randomString.ToString()
   End Function

End Module