Replace 5th vowel

[angelica]

Hey,

I need to find the first letter in a message and replace it with the 5th vowel in another string. However it never gets into the condition in Red Color. Any help please ?

I also need to keep the count of the characters in the characterarray. ???

Private Sub Find5vowel()

        Dim vowelcounter, i As Integer
        Dim characterarray() As Char
        Dim vowelarray() As Char = {"a", " A", "e", "i", "I", "o", "O", "u", " U", "E"}
        Dim strmessage1 As String
        'RandomGen1 is a string of 200 letters which has been randomized
        characterarray = RandomGen1.ToCharArray()
        For i = 1 To characterarray.Length

            If vowelarray = characterarray(i) Then
                vowelcounter += 1           
              If vowelcounter = 5 Then 
                    letter5vowel = characterarray(i)
                    strmessage1 = characterarray.ToString
                    strmessage1 = strmessage1.Replace(letter5vowel, firstmessage)

                End If
            End If
        Next

                MessageBox.Show(strmessage1)

    End Sub

    Private Sub Findfirst()
        Try

            If txtmessage.Text = String.Empty Then
                MessageBox.Show("Message cannot be left empty!")
            Else
                strmessage = txtmessage.Text
                Dim messagearray() As Char

                messagearray = strmessage.ToCharArray()
                firstmessage = messagearray(0)
                ' MessageBox.Show(firstmessage)
            End If
        Catch ex As Exception
            MessageBox.Show(ex.ToString)
        End Try

    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Findfirst()
        Find5vowel()

    End Sub

[jmcilhinney]

Have you stepped through your code? The only reason that execution won't enter an If block is because the condition evaluates to False. If you step through your code and examine the values of your variables at each step then it should be fairly obvious why an expression evaluates to False.

[Vectris]

Just a tip, but you can shorten your vowelarray to only uppercase and just use .ToUpper() in your code, like:

 If vowelarray = characterarray(i).ToUpper() Then

That way it will run faster. Also, if you just store all the vowels to a string, like this:

Dim vowelString as String = "AEIOUY"

Then you can just use:

If vowelString.Contains(characterarray(i).ToUpper())

So you don't even need to loop through the vowel array, just use .contains to see if it has a vowel.

[angelica]

Yes I did and plenty of vowels have been generated (out of 200!) so there must be something else.

[angelica]

Heya Vectris,

If vowelstring.Contains(characterarray(i).ToUpper())

get an error there! ToUpper does not accept the number of arguments

[Vectris]

huh, I didn't test it but I never remember ToUpper having any parameters. Try declaring a string, store the characterarray(i) to the string, then use .ToUpper() on the string and put that inside the ( ) for contains.

[jmcilhinney]

Heya Vectris,

If vowelstring.Contains(characterarray(i).ToUpper())

get an error there! ToUpper does not accept the number of arguments

characterarray(i) is presumably a Char and Char.ToUpper is a Shared method, not an instance method, and it takes a single Char as an argument, i.e. the character you want to convert to upper case.

[angelica]

Heya,

Thanks for the last clue Vectris. Looks like I need some more help please.

I have changed some code as Vetris suggested and is working fine now But
the strmessage1 is not returning a string with the alterations as I expected but gives a message with "System Char []



...............

Dim strmessage1 As String
'RandomGen1 is a string of 200 letters which has been randomized
characterarray = RandomGen1.ToCharArray()
For i = 1 To characterarray.Length

If vowelstring.Contains(characterarray(i).ToString.ToUpper()) Then
vowelcounter += 1
If vowelcounter = 5 Then
letter5vowel = characterarray(i)
strmessage1 = characterarray.ToString
strmessage1 = strmessage1.Replace(letter5vowel, firstmessage)
Exit For

End If


End If

Next
MessageBox.Show(strmessage1)

End Sub[/CODE]

PS

Could it be that the :
If vowelstring.Contains(characterarray(i).ToString.ToUpper()) Then

is logically incorrect. I need to check whether characterarry contains and vowels (vowelstring) not the other way round,but when I tried to twist it round I still got an empty message

[Vectris]

check this line

 strmessage1 = characterarray.ToString

You forgot the index

 strmessage1 = characterarray(i).ToString

EDIT: Wait, what you trying to do here?

                    strmessage1 = characterarray.ToString
                    strmessage1 = strmessage1.Replace(letter5vowel, firstmessage)

The first line stores something to strmessage1, but the second line will store right over it making that first line useless.

Also, you never declare letter5vowel, where is that part? Same for firstmessage.

[Vectris]

I'm guessing that you were trying to display the random 200 letter word with the 5th vowel replaced with whatever firstmessage was (I'm also assuming that letter5vowel is a String, if not, you might have to use the .ToString() method). In that case change this part:

                    letter5vowel = characterarray(i)
                    strmessage1 = characterarray.ToString
                    strmessage1 = strmessage1.Replace(letter5vowel, firstmessage)

to

                    letter5vowel = characterarray(i)
                    strmessage1 = RandomGen1.Replace(letter5vowel, firstmessage)

But just to let you know, this will replace every vowel in the entire word that matches letter5vowel. So if the 5th vowel is "e", then no just the 5th "e" will be replaced, but all of the "e"s will be. To remove just the 5th e you need to record the index of the 5th value, just store your i variable to an integer called fifthIndex or something and then I think you can use the parameters of Replace for where to start and for how many characters to replace starting from that position.

[angelica]

Heya,

I am not sure how to use the index. Not quite familiar with the syntax here. I have tried the code below but it seems it is replaces all occurances of the same vowel.Can someone pls tell what Im doing wrong?


Dim index5th As Integer = RandomGen1.IndexOf(characterarray(i))
strmessage1 = RandomGen1.Replace(RandomGen1(index5th), firstmessage)

[angelica]

<bump>

[ForumAccount]

If this isn't homework you could use this:

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load 
        Dim RandomStr As String = "KGNJHBGBHASDJGHABWEKWHGLHEABNGLWEABGLAEWHBGHABGAJWKEBHGLAWHEGBLAEVBALENBLGABEWGLEGBALGWHEOIQTUIWEHGJKEBGNMZX" 
        Dim Vowels As String = "AEIOU" 
        Dim VowelNum, Index As Integer 
        Do While VowelNum < 5 And Index <> RandomStr.Length 
            If Vowels.Contains(RandomStr.Substring(Index, 1).ToUpper) Then 
                VowelNum += 1 
            End If 
            Index += 1 
        Loop 
        If VowelNum = 5 Then 
            MsgBox("Fifth vowel: " & RandomStr.Substring(Index - 1, 1) & " was char number " & Index & " in the string.") 
        Else 
            MsgBox("There is no fifth vowel.") 
        End If 
End Sub

This just finds the fifth vowel, you will still have to replace it in your message. (I didn't want to steal all the fun)

[angelica]

hey ,


The above code gives a NullReferenceException. ???

I need some help in the replacing please.

[ForumAccount]

Let's go one step at a time (replacing later). Be specific about where the above code gives an Exception. Post your code showing how you are using it... because it works fine for me.

[angelica]

Okay ,

I was not refering to my RandomGenerator in your code correctly. Now it is working fine.

Now I need to replace the RandomGenerator (200 char) + the index of the 5th vowel in the 2nd block of the same index generator (same RandomGenerator. Below is your code with my altertions

RandomGenerator1()
        Dim RandomStr As String = RandomGen1
        Dim Vowels As String = "AEIOU"
        Dim VowelNum, Index As Integer
        Do While VowelNum < 5 And Index <> RandomStr.Length
            If Vowels.Contains(RandomStr.Substring(Index, 1).ToUpper) Then
                VowelNum += 1
            End If
            Index += 1
        Loop
        If VowelNum = 5 Then
            MsgBox("Fifth vowel: " & RandomStr.Substring(Index - 1, 1) & " was char number " & Index & " in the string.")
        Else
            MsgBox("There is no fifth vowel.")
        End If
    End Sub

Thanks for your help!