Microsoft Visual Basic 2010 Step by Step eBook

Chapter 13 Exploring Text Files and String Processing 335

The entire SortTextToolStripMenuItem_Click event procedure looks like this:

Dim strArray() As String

Dim sText As String

Dim i As Short

sText = txtNote.Text

'replace different new line characters with one version

sText = sText.Replace(vbCrLf, vbCr)

sText = sText.Replace(vbLf, vbCr)

'remove last carriage return if it exists

If sText.EndsWith(vbCr) Then

sText = sText.Substring(0, sText.Length - 1)

End If

'split each line in to an array

strArray = sText.Split(vbCr)

'sort array

ShellSort(strArray, strArray.Length)

'then display sorted array in text box

sText = ""

For i = 0 To strArray.Length - 1

sText = sText & strArray(i) & vbCrLf

Next i

txtNote.Text = sText

txtNote.Select(0, 0) 'remove text selection

The Split method creates an array that has the same number of elements as the text

box has lines of text. After the array is full of text, I call the ShellSort procedure located

in the Module1 .vb module, which I discussed earlier in this chapter. After the array is

sorted, I use a For loop (as discussed in Chapter 7) to reconstruct the lines and copy

them into the text box.

3. Display the code for the Module1 .vb module in the Code Editor.

This module defines the content of the ShellSort procedure. The ShellSort procedure

uses an If statement and the <= relational operator (as discussed in Chapters 6, 8,

and this chapter) to compare array elements and swap any that are out of order.

The procedure looks like this:

Sub ShellSort(ByVal sort() As String, ByVal numOfElements As Short)

Dim temp As String

Dim i, j, span As Short

'The ShellSort procedure sorts the elements of sort()

'array in descending order and returns it to the calling

'procedure.

span = numOfElements \ 2

Do While span > 0