Random lowercase letter

In ASCII there are 26 lowercase letters. We cannot generate these directly with the Random class. But we can use a Function to get them.

With VB.NET helper functions like Asc and Chr we convert the Integer returned by Random's Next Function. We manipulate the value of the random number.

Here is the example

We introduce a GetLetter Function. This returns a Char. We use a Random class instance field. We call Next() on the Random class.

Module Module1

    ' Used for GetLetter function.
    Dim _random As Random = New Random()

    Function GetLetter() As Char
        ' Get random number between 0 and 25 inclusive.
        ' ... The second argument 26 is exclusive.
        ' ... This corresponds to an ASCII char.
        Dim number As Integer = _random.Next(0, 26)
        ' Convert lowercase "a" to an Integer with Asc.
        ' ... Use this value to offset the number we generated.
        ' ... Convert back to a Char with Chr.
        Dim letter As Char = Chr((Asc("a"c) + number))
        Return letter
    End Function

    Sub Main()
        ' Use our GetLetter function 5 times.
        For i As Integer = 0 To 4
            Dim letter = GetLetter()
            Console.WriteLine(letter)
        Next
    End Sub

End Module
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With a Random field, we avoid repeating random sequences. When a method like GetLetter is called many times, it is important to avoid creating a new Random each time.

Some testing

After running this program many times, I find that it generates "a" through "z." And no other chars appear to be generated.

Some uses

Random lowercase letters can be used alongside a class like StringBuilder. We can generate random strings in this way.