类型匹配的值不能转换为字符串

Question

I'm currently trying to loop over a folder of text files and read them. After I've read them, I'd like to extract a certain portion of the name of the files using Regular Expressions, however I am getting the error Value of Type Match Cannot Be Converted To String .

I have tried using Cstr however this doesn't seem to solve my problem.

Code I am using:

 Dim fileentries As String() = Directory.GetFiles("D:\User\BackUp\Project\bin\Debug\Orders")
 For Each entry In fileentries
        Dim match As New List(Of String)
        Dim regexmatch As Match = Regex.Match(entry, "Order_\d\d-\d\d-[\d]{4}_[\d]{6}")
        match.Add(CStr(regexmatch))

    Next

Here the Regular Expressions section is working, it seems to extract the correct portion of the filename I want however specifically with line match.Add(Cstr(regexmatch)) I am getting the error I've described.

Any help is appreciated, thank you.

Answer 1

You need to access the .Value property of the Match object, but it is recommended to check if there is a match at all:

Dim regexmatch As Match = Regex.Match(entry, "Order_\d\d-\d\d-\d{4}_\d{6}")
If regexmatch.Success Then
    match.Add(regexmatch.Value)
End If

See the VB.NET demo :

Imports System.Collections.Generic
Imports System.Text.RegularExpressions
' ... 
Dim match As New List(Of String)()
Dim entry As String = "XXXX_Order_12-12-1234_123456_irrelevant.txt"
Dim regexmatch As Match = Regex.Match(entry, "Order_\d\d-\d\d-\d{4}_\d{6}")
If regexmatch.Success Then
    match.Add(regexmatch.Value)
End If
Console.WriteLine(match(0)) ' => Order_12-12-1234_123456

Note that [\\d]{4} is equal to \\d{4} , no need to put a single atom into a character class.