将正则表达式匹配项添加到数组

Question

I'm struggling to solve a small bit of code. What the code does is to first load a CSV file, line by line (starting by line 3), and add it to an array. Then run a regex match and I want to insert the value in an array.

This is my working code, it shows a msgbox with the actual matches:

Dim file = "C:\Users\David\Desktop\mycsv.csv"
    Dim basestatisticspath = Path.GetDirectoryName(file)
    Dim statistics() As String = IO.File.ReadAllLines(file)
    'Dim x As Integer = statistics.Length
    'ReDim Preserve statistics(x)

    Dim regexlang As Regex = New Regex("(?<=^"")\[.*\]")
    Dim regexlinefilename As Regex = New Regex("(?<=^""\[.*?\]\s).*(?="")")
    Dim linefilename As Match = Nothing
    Dim langmatch As Match = Nothing
    Dim filename() As String
    Dim lang() As String

    For i = 2 To UBound(statistics)
        langmatch = regexlang.Match(statistics(i))
        linefilename = regexlinefilename.Match(statistics(i))
        MsgBox(langmatch.Value & linefilename.Value)
    Next

That works well and the actual matches is what I want. So my next step was to add each match to an array to then use it to generate other files.

Therefore I ended up with this:

    Dim file = "C:\Users\David\Desktop\myscv.csv"
    Dim basestatisticspath = Path.GetDirectoryName(file)
    Dim statistics() As String = IO.File.ReadAllLines(file)
    'Dim x As Integer = statistics.Length
    'ReDim Preserve statistics(x)

    Dim regexlang As Regex = New Regex("(?<=^"")\[.*\]")
    Dim regexlinefilename As Regex = New Regex("(?<=^""\[.*?\]\s).*(?="")")
    Dim linefilename As Match = Nothing
    Dim langmatch As Match = Nothing
    Dim filename() As String
    Dim lang() As String

    ' Set all value line by line
    For i = 2 To UBound(statistics)
        langmatch = regexlang.Match(statistics(i))
        linefilename = regexlinefilename.Match(statistics(i))
        lang(i) = langmatch.Value.ToString
        filename(i) = linefilename.Value.ToString
        MsgBox(langmatch.Value & linefilename.Value)

    Next

After adding the below the program crashes on that line

    lang(i) = langmatch.Value.ToString
    filename(i) = linefilename.Value.ToString

I am assuming you can add the value of a regex match to a certain position of a string, but it seems I am wrong.

I´ve been searching for an answer with no results (at least to my poor understanding).

How could I convert each of the matches to a string and add it to the i position of the array?

Thanks in advance!

UPDATE: As @Tval explained, I solved it by including the size of the array when declaring it. Thanks!

    Dim filename(UBound(statistics)) As String
    Dim lang(UBound(statistics)) As String

Answer 1

you need to initialize the array before you can reference it or you'll get a null reference error, also you can't reference an index that doesn't exist yet or you'll get an index out of range exception.

right now your using an array with a fixed length, so if you want to add a value to it you'll have to re-declare it one index larger every time.

If you want an array of a variable length id suggest using a list, so you can just append values to it without any issues

Dim myList = New List(Of String)
For Each foo As String In bar
    myList.Add(bar)
Next