displaying a word backwards vb

Question

i've been trying to figure this out for the last hour, i almost got it to work, but it just displays the word un-reversed. I don't know why this is. I know its a beginner question but please help. Thanks.

Private Sub btnReverse_Click(sender As Object, e As EventArgs) Handles btnReverse.Click

    Dim strInput As String
    Dim strLetter As String
    Dim intLength As Integer

    strInput = txtWord.Text
    intLength = strInput.Length
    '!!de-incremented because index starts at 0!!
    intLength = intLength - 1

    Dim indexReverse As Integer = intLength

    For index As Integer = 0 To intLength Step +1
        'get letter at this index
        strLetter = strInput.Substring(index, 1)
        'remove letter just got
        strInput = strInput.Remove(index, 1)
        'insert new letter at old letter place
        strInput = strInput.Insert(indexReverse, strLetter)

        indexReverse = indexReverse - 1
    Next

    lblReverse.Text = strInput

End Sub

Ok so i edited my code as per kjtl's idea, now im getting an argumentoutofrange exeption. I know what that means but i dont understand why im getting that exeption. To reiterate, i want to Edit this code as little as possible to get it to work. Both ideas were easier ways of doing this, i just want to fix my code without replacing it all for educational purposes.

Private Sub btnReverse_Click(sender As Object, e As EventArgs) Handles btnReverse.Click

    Dim strInput As String
    Dim strOutput As String = ""
    Dim strLetter As String
    Dim intLength As Integer
    Dim chrPadding As Char = Convert.ToChar(" ")

    strInput = txtWord.Text
    intLength = strInput.Length
    '!!de-incremented because index starts at 0!!
    intLength = intLength - 1

    Dim indexReverse As Integer = intLength

    For index As Integer = 0 To intLength Step +1
        'get letter at this index
        strLetter = strInput.Substring(index, 1)
        'assign temp values to strOutput
        strOutput = strOutput.PadRight(intLength, chrPadding)
        'remove letter just got
        strOutput = strOutput.Remove(index, 1)
        'insert new letter at old letter place
        strOutput = strOutput.Insert(indexReverse, strLetter)

        indexReverse = indexReverse - 1
    Next

    lblReverse.Text = strInput

End Sub

The string you are using to store the result is the same string you are using to feed the loop. Try using a different string for the output. — Keith John Hutchison, Mar 26 '14 at 23:42
Wow both methods are easier. But just for educational purposes, can you make the code i wrote work? Its been killin me. — 0000, Mar 27 '14 at 00:02
Please don't reinvent the wheel. Especially when the code you write does not introduce any performance or readability improvement. Good learning example is optimizing the Sort function, to use Shell sort or any other "advanced" sorting mechanism. There is no point in rewriting a 20 character solution in 200 characters and make it do the same thing, or even slower than the short method. — Victor Zakharov, Mar 27 '14 at 01:10
The other methods are better ... and you're doing way to much with strOutput. strOutput = strLetter + strOutput is all that is required. — Keith John Hutchison, Mar 27 '14 at 06:15

Steve · Accepted Answer · 2014-03-26T23:48:39.723

4

The Array class has a Reverse method that

Reverses the sequence of the elements in the entire one-dimensional Array

Now, the string class has a method that extract the single char elements of the string as an array of chars. At this point the solution is really simple.

Dim strInput = "This is a Test"
Dim c = test.ToCharArray()
Array.Reverse(c)
Dim reversed = new String(c)
Console.WriteLine(reversed)

Or if you like a one liner solution

Dim strInput = "This is a Test"
Dim reversed = new String(strInput.ToCharArray().Reverse().ToArray())

edited Mar 26 '14 at 23:48

answered Mar 26 '14 at 23:39

Steve

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1

The String class has a `Reverse()` method. There's no need to cast to a char array. – Sam Axe Mar 27 '14 at 01:26
Well, an extension method anyhow. – Sam Axe Mar 27 '14 at 01:28

score 3 · Answer 2 · edited May 23 '17 at 10:09

3

You can use StrReverse:

Dim str As String = "hello"
Dim strRev As String = StrReverse(str) 'olleh

Or this (if you prefer to avoid using VisualBasic namespace):

Dim strRev2 As New String(str.Reverse.ToArray) 'olleh

displaying a word backwards vb

2 Answers2