When I do the following....
Dim s As String = ""
Dim sLines() As String = s.Split("|", StringSplitOptions.None)
...
sLines.Count is 1.
Why?
There is nothing to split, and the string to be split is empty, so I would expect sLines.Count to be 0.
Thank you.
A sort of consistency: if "a|b" split on | is ["a", "b"] and "a" split on | is ["a"], it makes some sense for "|b" split on | to be ["", "b"] and "" split on | to be [""].
You can remove all empty entries by passing StringSplitOptions.RemoveEmptyEntries instead of None, or just check for s = String.Empty manually otherwise.
Check the documentation of Split:
If this instance does not contain any of the strings in separator, the returned array consists of a single element that contains this instance.
This is your case. "" doesn't contain "|", so a single element "" is returned.
You can use IIf() function to handle empty string
Dim s As String = ""
Dim sLines() As String = IIf(s = String.Empty, Nothing, s.Split("|"))
Dim cnt As Integer
If sLines IsNot Nothing Then
'your code
cnt = sLines.Count
Else
'your code
cnt = 0
End If
Note: In case if you want to handle white spaces(Dim s As String = " ") just use trim() like this
IIf(Trim(s) = String.Empty, Nothing, s.Split("|"))
Related
I have a String file with 8 items (separated by commas) in each row, e.g., CA,23456,aName,aType,anotherName,aWord,secondword,number. I want to create a new string of items consisting of the 2nd item (an Integer) of each row of the original file. I know there are many ways to do this but someone out there knows how to do it with very few lines of code, which is what I am looking for. I prefer not to use a parser.
The way to show what I have tried is to look at the code below.
Dim sn2 As String = ""
Dim sn2S As String = ""
Using readFile As New StreamReader(newFile1)
Do While readFile.Peek() <> -1
sn2S = readFile.ReadLine(1)
sn2 = sn2 & sn2S & ","
Loop
End Using
The code returns the second character of each row not the second item. What I hope to get is a string that looks like: 123,1345,4325,3321,3456,3211 etc. Where each number is the second item in each row of the original file.
You could split it up by cells
Dim row As String = "CA,23456,aName,aType,anotherName,aWord,secondword,number"
Dim cells() As String = row.Split(",")
Dim cellValue As String = cells(1)
But in your case, I would just do a search and Substring by the index of the delimiter.
Dim startPosition As Integer = row.IndexOf(",") + 1
Dim endPosition As Integer = row.IndexOf(",", startPosition)
Dim cellValue As String = row.Substring(startPosition, endPosition - startPosition)
If you have the whole file in memory, there could be some regex that could do the job with one pass.
As for this line
sn2 = sn2 & sn2S & ","
You might want to check at doing a join or using stringbuilder.
You could try
Dim sn2 As String = ""
Dim sn2S(7) As String = ""
Using readFile As New StreamReader(newFile1)
Do While readFile.Peek() <> -1
Array.Clear(sn25,0,sn25.Length)
sn2S = readFile.ReadLine(1).Split(",")
sn2 = sn2 & sn2S(1) & ","
Loop
End Using
In one line
Dim sn2 = String.Join(",", File.ReadAllLines(newFile1).Select(Function(s) s.Split(","c)(1)))
From the inside-out:
File.ReadAllLines(newFile1) splits the file into lines and results in a string array holding those lines, which is fed into...
...Select(Function(s) s.Split(","c)(1)) which operates on each line by splitting the line by comma s.Split(","c) and then indexing the resulting array (1) to return the second (zero-based) element. This is fed into...
String.Join(",", ... ) which takes those second elements and joins then together with comma.
I'm a programing student, so I've started with vb.net as my first language and I need some help.
I need to know how I delete excess white spaces between words in a sentence, only using these string functions: Trim, instr, char, mid, val and len.
I made a part of the code but it doesn't work, Thanks.
enter image description here
Knocked up a quick routine for you.
Public Function RemoveMyExcessSpaces(str As String) As String
Dim r As String = ""
If str IsNot Nothing AndAlso Len(str) > 0 Then
Dim spacefound As Boolean = False
For i As Integer = 1 To Len(str)
If Mid(str, i, 1) = " " Then
If Not spacefound Then
spacefound = True
End If
Else
If spacefound Then
spacefound = False
r += " "
End If
r += Mid(str, i, 1)
End If
Next
End If
Return r
End Function
I think it meets your criteria.
Hope that helps.
Unless using those VB6 methods is a requirement, here's a one-line solution:
TextBox2.Text = String.Join(" ", TextBox1.Text.Split(New Char() {" "c}, StringSplitOptions.RemoveEmptyEntries))
Online test: http://ideone.com/gBbi55
String.Split() splits a string on a specific character or substring (in this case a space) and creates an array of the string parts in-between. I.e: "Hello There" -> {"Hello", "There"}
StringSplitOptions.RemoveEmptyEntries removes any empty strings from the resulting split array. Double spaces will create empty strings when split, thus you'll get rid of them using this option.
String.Join() will create a string from an array and separate each array entry with the specified string (in this case a single space).
There is a very simple answer to this question, there is a string method that allows you to remove those "White Spaces" within a string.
Dim text_with_white_spaces as string = "Hey There!"
Dim text_without_white_spaces as string = text_with_white_spaces.Replace(" ", "")
'text_without_white_spaces should be equal to "HeyThere!"
Hope it helped!
What I want to do is replace all 'A' in a string with "Bb". but it will only loop with the original string not on the new string.
for example:
AAA
BbAA
BbBbA
and it stops there because the original string only has a length of 3. it reads only up to the 3rd index and not the rest.
Dim txt As String
txt = output_text.Text
Dim a As String = a_equi.Text
Dim index As Integer = txt.Length - 1
Dim output As String = ""
For i = 0 To index
If (txt(i) = TextBox1.Text) Then
output = txt.Remove(i, 1).Insert(i, a)
txt = output
TextBox2.Text += txt + Environment.NewLine
End If
Next
End Sub
I think this leaves us looking for a String.ReplaceFirst function. Since there isn't one, we can just write that function. Then the code that calls it becomes much more readable because it's quickly apparent what it's doing (from the name of the function.)
Public Function ReplaceFirst(searched As String, target As String, replacement As String) As String
'This input validation is just for completeness.
'It's not strictly necessary.
'If the searched string is "null", throw an exception.
If (searched Is Nothing) Then Throw New ArgumentNullException("searched")
'If the target string is "null", throw an exception.
If (target Is Nothing) Then Throw New ArgumentNullException("target")
'If the searched string doesn't contain the target string at all
'then just return it - were done.
Dim foundIndex As Integer = searched.IndexOf(target)
If (foundIndex = -1) Then Return searched
'Build a new string that replaces the target with the replacement.
Return String.Concat(searched.Substring(0, foundIndex), replacement, _
searched.Substring(foundIndex + target.Length, searched.Length - (foundIndex + target.Length)))
End Function
Notice how when you read the code below, you don't even have to spend a moment trying to figure out what it's doing. It's readable. While the input string contains "A", replace the first "A" with "Bb".
Dim input as string = "AAA"
While input.IndexOf("A") > -1
input = input.ReplaceFirst(input,"A","Bb")
'If you need to capture individual values of "input" as it changes
'add them to a list.
End While
You could optimize or completely replace the function. What matters is that your code is readable, someone can tell what it's doing, and the ReplaceFirst function is testable.
Then, let's say you wanted another function that gave you all of the "versions" of your input string as the target string is replaced:
Public Function GetIterativeReplacements(searched As String, target As String, replacement As String) As List(of string)
Dim output As New List(Of String)
While searched.IndexOf(target) > -1
searched = ReplaceFirst(searched, target, replacement)
output.Add(searched)
End While
Return output
End Function
If you call
dim output as List(of string) = GetIterativeReplacments("AAAA","A","Bb")
It's going to return a list of strings containing
BbAAA, BbBbAA, BbBbBbA, BbBbBbBb
It's almost always good to keep methods short. If they start to get too long, just break them into smaller methods with clear names. That way you're not trying to read and follow and test one big, long function. That's difficult whether or not you're a new programmer. The trick isn't being able to create long, complex functions that we understand because we wrote them - it's creating small, simpler functions that anyone can understand.
Check your comments for a better solution, but for future reference you should use a while loop instead of a for loop if your condition will be changing and you're wanting to take that change into account.
I've made a simple example below to help you understand. If you tried the same with a for loop, you'd only get "one" "two" and "three" printed because the for loop doesn't 'see' that vals was changed
Dim vals As New List(Of String)
vals.Add("one")
vals.Add("two")
vals.Add("three")
Dim i As Integer = 0
While i < vals.Count
Console.WriteLine(vals(i))
If vals(i) = "two" Then
vals.Add("four")
vals.Add("five")
End If
i += 1
End While
If you do want to replace one by one instead of using the Replace function, you could use a while loop to look for the index of your search character/string, and then replace/insert at that index.
Sub Main()
Dim a As String = String.Empty
Dim b As String = String.Empty
Dim c As String = String.Empty
Dim d As Int32 = -1
Console.Write("Whole string: ")
a = Console.ReadLine()
Console.Write("Replace: ")
b = Console.ReadLine()
Console.Write("Replace with: ")
c = Console.ReadLine()
d = a.IndexOf(b)
While d > -1
a = a.Remove(d, b.Length)
a = a.Insert(d, c)
d = a.LastIndexOf(b)
End While
Console.WriteLine("Finished string: " & a)
Console.ReadLine()
End Sub
Output would look like this:
Whole string: This is A string for replAcing chArActers.
Replace: A
Replace with: Bb
Finished string: This is Bb string for replBbcing chBbrBbcters.
I was going to write a while loop to answer your question, but realized (with assistance from others) that you could just .replace(x,y)
Output.Text = Input.Text.Replace("A", "Bb")
'Input = N A T O
'Output = N Bb T O
Edit: There is probably a better alternative, but i quickly jotted this loop down, hope it helps.
You've said your new and don't fully understand while loops. So if you don't understand functions either or how to pass arguments to them, I'd suggest looking that up too.
This is your Event, It can be a Button click or Textbox text change.
'Cut & Paste into an Event (Change textboxes to whatever you have input/output)
Dim Input As String = textbox1.Text
Do While Input.Contains("A")
Input = ChangeString(Input, "A", "Bb")
' Do whatever you like with each return of ChangeString() here
Loop
textbox2.Text = Input
This is your Function, with 3 Arguments and a Return Value that can be called in your code
' Cut & Paste into Code somewhere (not inside another sub/Function)
Private Function ChangeString(Input As String, LookFor As Char, ReplaceWith As String)
Dim Output As String = Nothing
Dim cFlag As Boolean = False
For i As Integer = 0 To Input.Length - 1
Dim c As Char = Input(i)
If (c = LookFor) AndAlso (cFlag = False) Then
Output += ReplaceWith
cFlag = True
Else
Output += c
End If
Next
Console.WriteLine("Output: " & Output)
Return Output
End Function
Below a script I used in my SSIS package.
If (Row.AnswerType.Trim().ToUpper = "MULTIPLE SELECT" And _
Row.SurveyQuestionID = Row.SurveyDefinitionDetailQuestionNumber) Then
Dim Question1 As String = Row.SurveyDefinitionDetailAnswerChoices.ToUpper.Trim()
Dim ans1 As String = Row.SurveyAnswer.ToUpper.Trim()
For Each x As String In ans1.Split(New [Char]() {CChar(vbTab)})
If Question1.Contains(x) Then
Row.IsSkipped = False
Else
Row.IsSkipped = True
'Row.IsAllowed = True
Row.ErrorDesc = "Invalid Value in Answer Column For Multiple Select!"
End If
Next
End If
This script only succeeds when having a tab as delimiter. But I need both tab and non tab characters as delimiters.
Add all the needed characters to the character array
ans1.Split(New [Char]() { CChar(vbTab), CChar(" "), CChar(";") })
Or
ans1.Split(New [Char]() { CChar(vbTab), " "C, ";"C })
by using the character literal suffix C.
I have a text in database which is "computer-hardware". I used that code to split
' string seperated by colons '-'
Dim info As String = strcotegory
Dim arInfo As String() = New String(3) {}
' define which character is seperating fields
Dim splitter As Char() = {"-"c}
arInfo = info.Split(splitter)
For x As Integer = 0 To arInfo.Length - 1
Response.Write(arInfo(x) & "</br> ")
Next
but now I want to get "computer" in textbox1 and "hardware" in textbox2.
please guide me
If I understood you correctly, replace the For loop with the following lines of code:
textbox1.Text = arInfo(0)
textbox2.Text = arInfo(1)
By the way, initializing arInfo (... = New String(3) {}) is not necessary, since you overwrite the value of arInfo anyway (arInfo = ...).