Count specific character in string using SubString

Question

I'm teaching myself VB.net and I'm trying to complete challenges.

I'm stuck on this challenge.

I'm trying to figure out how to go about counting specific characters in a string using SubString.

I should not use string processing functions other than: Trim, ToUpper, ToLower, Indexof, SubString.

Add one button for each vowel of the alphabet. When clicked, the output is the count of that vowel in the text entered.Using SubString, the code under the button click event handler,displays how many times the corresponding character appears in the text.

This is what I have so far, but how should I incorporate SubString?

    Dim counter As Integer = 0
    For Each vowelA As Char In TextBox1.Text
        If vowelA = "a" Then
            counter += 1
        End If

        If vowelA = "A" Then
            counter += 1
        End If

    Next

Looks more like homework ;0)

David Wilson
– David Wilson

2016-01-23 17:09:14 +00:00
Commented Jan 23, 2016 at 17:09 — David Wilson
– David Wilson, Commented Jan 23, 2016 at 17:09

Aethan · Accepted Answer · 2016-01-23 03:46:32Z

2

Here I incorporated also .ToUpper so you don't need to compare "a" and "A"

Dim counter As Integer = 0
For i = 0 To TextBox1.Text.Length - 1
    If TextBox1.Text.ToUpper.Substring(i, 1) = "A" Then
        counter += 1
    End If
Next

edited Jan 23, 2016 at 3:46

answered Jan 23, 2016 at 3:33

Aethan

1,9852 gold badges19 silver badges25 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

CodingIsHardForMe Over a year ago

Thanks so much! I just had to fix up a bit of your code cause it didn't originally work

CodingIsHardForMe Over a year ago

I had to make it Textbox1.Text.Length - 1

Vivek S. · Accepted Answer · 2016-01-23 09:38:22Z

1

Without using a substring() function,

 Function count_vowels(ByVal str As String, ByVal chr As String) As Integer
        str = str.ToUpper()
        chr = chr.ToUpper()
        count_vowels = str.Split(chr).Length - 1
        Return count_vowels
 End Function

Usage:

Dim counter As Integer = 0
counter = count_vowels(TextBox3.Text, "a")

or simply use

 counter = TextBox1.Text.ToUpper.Split("a".ToUpper).Length - 1

edited Jan 23, 2016 at 9:38

answered Jan 23, 2016 at 4:30

Vivek S.

22.3k9 gold badges71 silver badges87 bronze badges

4 Comments

CodingIsHardForMe Over a year ago

I don't see SubString anywhere here.

Vivek S. Over a year ago

This method doesn't need substring that's why you can't see it

CodingIsHardForMe Over a year ago

The question states to specfically use SubString

Vivek S. Over a year ago

Yeah I can see that.IMO nothing hurt to post an answer that solves a question..If you don't want to take this as answer let it be, future visitors might found this useful

Serge · Accepted Answer · 2016-01-23 03:27:41Z

0

Try something like this:

    Dim pos As Integer = 0
    Dim letter as String
    While pos < TextBox1.Text.Length
        letter = TextBox1.Text.Substring(pos, 1)
        If letter = "A" Then
            counter += 1
        End If

        pos += 1
    End While

answered Jan 23, 2016 at 3:27

Serge

4,0662 gold badges20 silver badges39 bronze badges

1 Comment

Serge Over a year ago

This is just an example that shows how to use Substring. It should count all upper-case letters "A".

Collectives™ on Stack Overflow

Count specific character in string using SubString

3 Answers 3

2 Comments

4 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

4 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related