Splitting a string based on a set length of characters - vb.net

Question

MVC 3. Vb.net. Part of my app generates PDF files using Itextsharp. Some strings are too long to go onto the background image correctly. So I basically need to split this string when its over 26 characters long and when it splits it cant split in the middle of a word. from there I will use newline to add the string to the right to the next line... Any ideas that might point me in the right direction.. I did start bulding the function that I will pass the string into test for length and then pass back the string after it finishes but I am stummped after that..
Private Function stringLength(ByVal _string As String) As String
If _string.Length < 26 Then
_string.Split(
End If
End Function

Answer 1

I'm sure there's a million different ways to do this.
You basically need to get all of your words split by the space into a list. After that, you just need to keep checking if the current word plus a space plus the next word reach your threshold or not, and if it does, you move to the next line. Once you have all of your lines, then you rejoin the list into a single string again.
Private Function LimitWidth(ByVal text As String, ByVal maxCharacters As Integer) As String
Dim words As List(Of String) = text.Split(" "c).ToList()
If text.Length < maxCharacters OrElse words.Count = 1 Then
Return text
Else
Dim lines As New List(Of String)
Dim currentLine As String = words(0)
For i As Integer = 1 To words.Count - 1
If (currentLine & " " & words(i)).Length > maxCharacters Then
lines.Add(currentLine)
currentLine = words(i)
If i = words.Count - 1 Then
lines.Add(currentLine)
End If
Else
If i = words.Count - 1 Then
lines.Add(currentLine & " " & words(i))
End If
currentLine &= " " & words(i)
End If
Next
Return String.Join(Environment.NewLine, lines.ToArray())
End If
End Function
To Test:
Private Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click
MessageBox.Show(LimitWidth("This is a really long sentence " & _
"meant to demonstrate how to split " & _
"the words into a confined character length.", 26))
End Sub

Answer 2

It sounds like you are asking for a word wrap function.
Since I feel that it's better to answer in a way that promotes learning than to just give answers, I have for you a link that walks you through the process of using Test Driven Development (TDD) to solve this problem. It just so happens that the word wrap problem is a popular coding kata, and Robert C. Martin wrote a somewhat silly fictional story about a developer being taught how to use TDD to solve the word wrap kata.
The code examples are in Java, but it should be trivial to read and translate.
http://thecleancoder.blogspot.com/2010/10/craftsman-62-dark-path.html
The goofy bits are skip-able. Just jump down to the sentences right before the first code snippet.

Answer 3

I would add to it handling of multiline input text with following:
Private Function LimitWidth(ByVal text As String, ByVal maxCharacters As Integer, SplitSign As String) As String
Dim Output As String = ""
Dim OrgLines As List(Of String) = text.Split(Environment.NewLine).ToList()
For x As Integer = 1 To OrgLines.Count - 1
Dim words As List(Of String) = OrgLines(x).Split(" "c).ToList()
If text.Length < maxCharacters OrElse words.Count = 1 Then
Output += OrgLines(x)
Else
Dim lines As New List(Of String)
Dim currentLine As String = words(0)
For i As Integer = 1 To words.Count - 1
If (currentLine & " " & words(i)).Length > maxCharacters Then
lines.Add(currentLine)
currentLine = words(i)
If i = words.Count - 1 Then
lines.Add(currentLine)
End If
Else
If i = words.Count - 1 Then
lines.Add(currentLine & " " & words(i))
End If
currentLine &= " " & words(i)
End If
Next
Output += String.Join(SplitSign, lines.ToArray())
End If
Next
Return Output
End Function
use:
LimitWidth("your text", 80, Environment.NewLine)