Extracting Vowels in Substring

[hans_cellc]

I am new to programming and am playing with VB.net.

I have a string:

Mary has a little lamb.

I want to extract the vowels only in order and display in a label as follows:

aaaiea

I am working towards a list of constanants as well as follows:
mryhslttllmb

but want to start with the first part.

I have googled and found no such problems.

Can anyone please help.

[cellus205]

You could create a List of vowels, and then check each character in the string on that list.

Dim vowelList as New List(Of String)
vowelList.Add("a")
vowelList.Add("e")
vowelList.Add("i")
vowelList.Add("o")
vowelList.Add("u")

If sometimes = True Then vowelList.Add("y")

Dim count as Integer = myString.Length - 1
Dim y as Integer = 0
For x = 0 to count 
   If vowelList.Contains(myString(y)) = True
        myString = myString.Remove(y, 1)
        y -= 1
   End If
   y += 1
Next

[hans_cellc]

Hi Thanks for reply, I started on this and had the same idea to check each character of the string but a slight diffirent approach.

Please check my code: what it does is sometimes it picks up a vowel and sometimes not, it does not pick up subsequent vowels and some word no vowels at all.

Private Sub Button_Sort_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button_Sort.Click
        Dim strInput As String, intCount As Integer = 1
        Dim ChaTemp As Char = ""
        Dim ChaList As String = ""
        strInput = LCase(Me.TextBox_Input.Text)
        Do While intCount <= strInput.Length
            ChaTemp = strInput.Substring(intCount, 1)
            If ChaTemp Like "a" OrElse ChaTemp Like "e" OrElse ChaTemp Like "i" OrElse ChaTemp Like "o" OrElse ChaTemp Like "u" Then
                ChaList = ChaList + ChaTemp

            End If
            intCount += intCount
        Loop
        Me.Label_VowelOutput.Text = ChaList
        Me.Button_Clear.Focus()

    End Sub

[hans_cellc]

I Got it:

I changed the substring to chars

Private Sub Button_Sort_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button_Sort.Click
        Dim strInput As String, intCount As Integer = 0
        Dim ChaTemp As Char = ""
        Dim ChaList As String = ""
        strInput = LCase(Me.TextBox_Input.Text)
        Do While intCount <= strInput.Length - 1
            ChaTemp = strInput.Chars(intCount)
            If ChaTemp Like "a" OrElse ChaTemp Like "e" OrElse ChaTemp Like "i" OrElse ChaTemp Like "o" OrElse ChaTemp Like "u" Then
                ChaList = ChaList + ChaTemp

            End If
            intCount = intCount + 1
        Loop
        Me.Label_VowelOutput.Text = ChaList
        Me.Button_Clear.Focus()

    End Sub

[cellus205]

Ah ok, I just noticed you needed to add the vowels to a new string.

Strings are zero based, since you start intCount at 1, then it will never check the first character (0). You'd want to start intCount at 1, then change the loop to check until strInput.Length - 1.

Also, since chaTemp is only one character, why not use "ChaTemp = "a" " instead of Like, since there wouldn't be anything on either side of the character.

[MattP]

This can be solved using RegEx pretty easily. Consonants would be the same way.

    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        Dim vowels = ExtractVowels("Mary had a little lamb", True)
    End Sub

    Private Shared Function ExtractVowels(inputString As String, includeY As Boolean) As String
        Dim pattern As String = If(includeY, "[^aeiouyAEIOUY$]", "[^aeiouAEIOU$]")
        Return String.Join(Nothing, System.Text.RegularExpressions.Regex.Split(inputString, pattern))
    End Function

Edit: Rather than writing out each of the consonants I made a method to check for the vowels and replace them with an empty string.

    Private Shared Function ExtractConsontant(inputString As String, includeY As Boolean) As String
        Dim pattern As String = If(includeY, "[aeiouyAEIOUY]", "[aeiouAEIOU]")
        Return System.Text.RegularExpressions.Regex.Replace(inputString, pattern, String.Empty).Replace(" ", String.Empty)
    End Function