How do I get content of list to be displayed or stored in one line.
I get the content but in one line each, I need it to be in one line all.
Dim ride as string
For Each ride In myListFlight
Console.WriteLine(ride)
Next
Are you looking for this?
Dim ride as string
ride = String.Join(",", ListOfStrings)
I think what you're looking for is the Aggregate linq function.
What aggregate does is combine entries using a Func. With strings, this can be as simple as:
Dim combined as string
combined = myList.Aggregate(Function(byval a, byval b) a & " " & b)
With custom classes, it becomes a bit trickier - you usually have to translate to some sort of 'addable' class (such as a string), like:
Dim intermediary as IEnumerable(Of string)
intermediary = myList.Select(Function(x) x.ToString())
Dim combined as string
combined = intermediary.Aggregate(... etc ...)
(Pardon if the syntax isn't 100% correct. I'm a C# dev, so my VB-Linq knowledge is a bit rusty.)
Related
I am trying to write, in order to export on txt file, information in two listbox with the same number of rows. I have to export them with the following format: Listbox1, Listbox2. In order to do this, I've tried to use the following code:
Using writer = New StreamWriter(SaveFileDialog1.FileName)
For Each o As Object In Form3.ListBox1.Items And Form3.ListBox2.Items
writer.WriteLine(o)
Next
End Using
I'm receiving the following error:
BC30452 Operator 'And' is not defined for types 'ListBox.ObjectCollection' and 'ListBox.ObjectCollection'.
I've also tried to perform three For Each loops, the first for the LB1, the second for the commas and the third for LB2, but I'm having it exported with content on single lines. How could I solve this?
If you use Enumerable.Zip, as suggested in another answer, then you can make the code more succinct by doing away with the explicit loop:
File.WriteAllLines(SaveFileDialog1.FileName,
Form3.ListBox1.
Items.
Cast(Of Object).
Zip(Form3.ListBox2.
Items.
Cast(Of Object),
Function(x1, x2) $"{x1}, {x2}"))
If you didn't use Zip then you can use a loop this way:
Dim items1 = Form3.ListBox1.Items
Dim items2 = Form3.ListBox2.Items
Using writer = New StreamWriter(SaveFileDialog1.FileName)
For i = 0 To Math.Min(items1.Count, items2.Count)
writer.WriteLine($"{items1(i)}, {items2(i)}")
Next
End Using
The Math.Min part is just in case there are different numbers of items in each ListBox. If you know there aren't then you can do away with that and just use one Count. If there might be different counts but you want to output all items then the code would become slightly more complex to handle that.
As the error message says, the syntax you attempted is simply not valid. There's no feature in VB.NET that does that sort of thing.
However, the .NET Framework API does provide a means for something similar, which would probably work in your case. See Enumerable.Zip(). You can use it like this:
Using writer = New StreamWriter(SaveFileDialog1.FileName)
For Each o As String In Form3.ListBox1.Items.Cast(Of Object).Zip(Form3.ListBox2.Items.Cast(Of Object), Function(x1, x2) x1 & ", " & x2)
writer.WriteLine(o)
Next
End Using
Since you said that both list boxes have the same number of items we can use the number of items in the first listbox less one (indexes start at zero) in a For loop.
I used a StringBuilder so the code does not have to throw away and create a new string on each iteration.
I used an interpolated string indicate by the $ preceding the string. This means I can insert variables in braces, right along with literals.
Call .ToString on the StringBuilder to write to the text file.
Private Sub SaveListBoxes()
Dim sb As New StringBuilder
For i = 0 To ListBox1.Items.Count - 1
sb.AppendLine($"{ListBox1.Items(i)}, {ListBox2.Items(i)}")
Next
File.WriteAllText("C:\Users\xxx\Desktop\ListBoxText.txt", sb.ToString)
End Sub
I've looked around but wasn't able to find an exact solution...
I have an identifier-type field that generally follows the format of XXX-YY-ZZZZZZZZ. Sometimes the number of X's and Z's will vary, but the YY's are always enclosed between the two hyphens. If I wanted to create another field using just the "YY", what would be the best function to use? There's also another reference table with the YYs listed that I intend to relate it to.
Thanks in advance.
Sounds like you want to split the string into an array. Try this out
Public Sub Example()
Dim ExampleStr As String: ExampleStr = "XXX-YY-ZZZZZZZZ"
Dim StrArray() As String
StrArray = Split(ExampleStr, "-")
Debug.Print StrArray(1) ' Return the second element
End Sub
I'm trying to perform file deletion but only on files that don't exist in a list.
Example:
Dim FilesToKeep As List(Of String) = MyFunctionThatPopulatesTheList
The FilesToKeep list consists of the filenames.
Here is where I'm having trouble, as these clause functions throw me off big-time.
Dim filesToDelete
filesToDelete = New DirectoryInfo(FilePath) _
.GetFiles("*", SearchOption.AllDirectories) _
.Where(Function(f) Not f.Attributes.HasFlag(FileAttributes.Hidden)) _
.Where(Function(f) Not FilesToKeep.ToString.Contains(f.Name)) _
.[Select](Function(f) New FileCollectionForDelete(f)).ToArray()
Two things I'm trying to do if you look at the bottom two lines of the DirectoryInfo function. I only want the files that do not exist in the FilesToKeep list. The second, is just a helper where I'm storing the information about the file.
But as it stands, filesToDelete returns every single file.
Thank you for your help.
=========== EDIT =============
After comments, I gave it another shot, but curious if anyone can offer opinion on stability of this function.
First, I created another variable called FilesToKeep2
Dim FilesToKeep2 As String = String.Join(",", FilesTOKeep.ToArray())
And my function I left how it was, as it isn't comparing the entire path, note the (f.Name).
So right now this seems to be working properly, but worried about gotcha's later on.
Would this function be as solid as iterating through each one individually?
The problem is this expression:
Function(f) Not FilesToKeep.ToString.Contains(f.Name)
The type of the FilesToKeep object is a List(Of String). Calling ToString on a List(Of String) returns the name of the type. Just remove that part of the expression and you'll be fine:
Function(f) Not FilesToKeep.Contains(f.Name)
Also, I think you're overthinking things with the final .Select(). Skip that (and the .ToArray() call) entirely.
Final code:
Dim FilesToKeep As List(Of String) = MyFunctionThatPopulatesTheList()
Dim filesToDelete = (New DirectoryInfo(FilePath)).GetFiles("*", SearchOption.AllDirectories).
Where(Function(f) Not f.Attributes.HasFlag(FileAttributes.Hidden)).
Where(Function(f) Not FilesToKeep.Contains(f.Name))
For Each fileName As String In filesToDelete
File.Delete(fileName)
Next
Regarding your edit: you're probably fine with that edit. However, you should know that commas are legal in file names, and therefore it's possible to create files that should be deleted, but will still match your string. For best results here, at least use a delimiter character that's not legal in file names.
I need your help, guys! :|
I've got myself a CSV file with the following contents:
1,The Compact,1.8GHz,1024MB,160GB,440
2,The Medium,2.4GHz,1024MB,180GB,500
3,The Workhorse,2.4GHz,2048MB,220GB,650
It's a list of computer systems, basically, that the user can purchase.
I need to read this file, line-by-line, into an array. Let's call this array csvline().
The first line of the text file would stored in csvline(0). Line two would be stored in csvline(1). And so on. (I've started with zero because that's where VB starts its arrays). A drop-down list would then enable the user to select 1, 2 or 3 (or however many lines/systems are stored in the file). Upon selecting a number - say, 1 - csvline(0) would be displayed inside a textbox (textbox1, let's say). If 2 was selected, csvline(1) would be displayed, and so on.
It's not the formatting I need help with, though; that's the easy part. I just need someone to help teach me how to read a CSV file line-by-line, putting each line into a string array - csvlines(count) - then increment count by one so that the next line is read into another slot.
So far, I've been able to paste the numbers of each system into an combobox:
Using csvfileparser As New Microsoft.VisualBasic.FileIO.TextFieldParser _
("F:\folder\programname\programname\bin\Debug\systems.csv")
Dim csvalue As String()
csvfileparser.TextFieldType = Microsoft.VisualBasic.FileIO.FieldType.Delimited
csvfileparser.Delimiters = New String() {","}
While Not csvfileparser.EndOfData
csvalue = csvfileparser.ReadFields()
combobox1.Items.Add(String.Format("{1}{0}", _
Environment.NewLine, _
csvalue(0)))
End While
End Using
But this only selects individual values. I need to figure out how selecting one of these numbers in the combobox can trigger textbox1 to be appended with just that line (I can handle the formatting, using the string.format stuff). If I try to do this using csvalue = csvtranslator.ReadLine , I get the following error message:
"Error 1 Value of type 'String' cannot be converted to '1-dimensional array of String'."
If I then put it as an array, ie: csvalue() = csvtranslator.ReadLine , I then get a different error message:
"Error 1 Number of indices is less than the number of dimensions of the indexed array."
What's the knack, guys? I've spent hours trying to figure this out.
Please go easy on me - and keep any responses ultra-simple for my newbie brain - I'm very new to all this programming malarkey and just starting out! :)
Structure systemstructure
Dim number As Byte
Dim name As String
Dim procspeed As String
Dim ram As String
Dim harddrive As String
Dim price As Integer
End Structure
Private Sub csvmanagement()
Dim systemspecs As New systemstructure
Using csvparser As New FileIO.TextFieldParser _
("F:\folder\programname\programname\bin\Debug\systems.csv")
Dim csvalue As String()
csvparser.TextFieldType = Microsoft.VisualBasic.FileIO.FieldType.Delimited
csvparser.Delimiters = New String() {","}
csvalue = csvparser.ReadFields()
systemspecs.number = csvalue(0)
systemspecs.name = csvalue(1)
systemspecs.procspeed = csvalue(2)
systemspecs.ram = csvalue(3)
systemspecs.harddrive = csvalue(4)
systemspecs.optical = csvalue(5)
systemspecs.graphics = csvalue(6)
systemspecs.audio = csvalue(7)
systemspecs.monitor = csvalue(8)
systemspecs.software = csvalue(9)
systemspecs.price = csvalue(10)
While Not csvparser.EndOfData
csvalue = csvparser.ReadFields()
systemlist.Items.Add(systemspecs)
End While
End Using
End Sub
Edit:
Thanks for your help guys, I've managed to solve the problem now.
It was merely a matter calling loops at the right point in time.
I would recommend using FileHelpers to do the reading.
The binding shouldn't be an issue after that.
Here is the Quickstart for Delimited Records:
Dim engine As New FileHelperEngine(GetType( Customer))
// To Read Use:
Dim res As Customer() = DirectCast(engine.ReadFile("FileIn.txt"), Customer())
// To Write Use:
engine.WriteFile("FileOut.txt", res)
When you get the file read, put it into a normal class and just bind to the class or use the list of items you have to do custom stuff with the combobox. Basically, get it out of the file and into a real class asap, then things will be easier.
At least take a look at the library. After using it, we use a lot more simple flat files since it is so easy, and we haven't written a file access routine since (for that kinda stuff).
http://msdn.microsoft.com/en-us/library/microsoft.visualbasic.fileio.textfieldparser.aspx
I think your main problem is understanding how arrays work (hence the error message).
You can use split and join functions to convert strings into and out of arrays
dim s() as string = split("1,2,3",",") gives and array of strings with 3 elements
dim ss as string = join(s,",") gives you the string back
Firstly, it's actually really good that you are using the TextFieldParser for reading CSV files - most don't but you won't have to worry about extra commas and quoted text etc...
The Readline method only gives you the raw string, hence the "Error 1 Value of type 'String' cannot be converted to '1-dimensional array of String'."
What you may find easier with combo boxes etc is to use an object (e.g. 'systemspecs') rather than strings. Assign the CSV data to the objects and override the "ToString" method of the 'systemspecs' class to display in the combo box how you want with formatting etc. That way when you handle the SelectedIndexChanged event (or similar) you get the "SelectedItem" from the combo box (which can be Nothing so check) and cast it as the 'systemspecs' to use it. The advantage is that you are not restricted to display the exact data in the combo etc.
' in "systemspecs"...
Public Overrides Function ToString() As String
Return Name ' or whatever...
End Function ' ToString
e.g.
dim item as new systemspecs
item.ID = csvalue(1)
item.Name = csvalue(2)
' etc...
combobox1.Items.Add(item)
Let me know if that makes sense!
PK :-)
In one of the ms-access table I work with we have a text field with a set size.
At the end of this field there is some extra code that varies depending on the situation.
I'm looking for a way to remove one of these code but even when the last part is truncated by the field maximum size.
Let's call the field "field" and the code I'm looking to remove "abc-longcode".
If I use the replace SQL function with the string abc-longcode the query will only work when the code is complete.
If I also want my update query (that does nothing but remove this specific code at the end of my field) to work on incomplete codes how would that translate into ms-SQL?
It would have to remove (or replace with "" to be precise) all of the following (example of course, not the real codes):
abc-longcode
abc-longcod
abc-longco
abc-longc
abc-long
abc-lon
abc-lo
abc-l
Obviously I could do that with several queries. Each one replacing one of the expected truncated codes... but it doesn't sound optimal.
Also, when the field is big enough to get all of the code, there can sometime be extra details at the end that I'll also want to keep so I cannot either just look for "abc-l" and delete everything that follows :\
This query (or queries if I can't find a better way) will be held directly into the .mdb database.
So while I can think of several ways to do this outside of a ms-sql query, it doesn't help me.
Any help?
Thanks.
You can write a custom VBA replace method that will replace any of the given cases {"abc-longcode", ... "abc-l"}. This is essentially the same tack as your "several queries" idea, except it would only be one query. My VBA is rusty, but something like:
public function ReplaceCodes(str as string) as string
dim returnString as string
returnString = str
returnString = replace(returnString,"abc-longcode","")
// ... etc...
ReplaceCodes = returnString
end function
I may have gotten the parameter order wrong on replace :)
I would use my own custom function to do this using the split function to get the first part of the string. You can then use that value in the update query.
Public Function FirstPart(thetext As String) As String
Dim ret As String
Dim arrSplitText As Variant
arrSplitText = Split(thetext, "-")
ret = arrSplitText(0)
FirstPart = ret
End Function
Can you use:
Left(FieldX,InStr(FieldX,"abc-")-1)
EDIT re Comment
If there is a space or other standard delimiter:
IIf(InStr(InStr(FieldX, "abc-"), FieldX, " ") = 0, Left(FieldX, InStr(FieldX, "abc-") - 1), Replace(FieldX, Mid(FieldX, InStr(FieldX, "abc-"), InStr(InStr(FieldX, "abc-"), FieldX, " ") - InStr(FieldX, "abc-")), ""))