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如何：查詢具有指定之屬性或名稱的檔案 (Visual Basic)

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這個範例示範如何在指定的樹狀目錄中尋找所有具有指定副檔名 (例如 ".txt") 的檔案。 它也會示範如何根據建立時間來傳回樹狀結構中的最新或最舊檔案。

範例

Module FindFileByExtension  
    Sub Main()  
  
        ' Change the drive\path if necessary  
        Dim root As String = "C:\Program Files\Microsoft Visual Studio 9.0"  
  
        'Take a snapshot of the folder contents  
        Dim dir As New System.IO.DirectoryInfo(root)  
  
        Dim fileList = dir.GetFiles("*.*", System.IO.SearchOption.AllDirectories)  
  
        ' This query will produce the full path for all .txt files  
        ' under the specified folder including subfolders.  
        ' It orders the list according to the file name.  
        Dim fileQuery = From file In fileList _  
                        Where file.Extension = ".txt" _  
                        Order By file.Name _  
                        Select file  
  
        For Each file In fileQuery  
            Console.WriteLine(file.FullName)  
        Next  
  
        ' Create and execute a new query by using  
        ' the previous query as a starting point.  
        ' fileQuery is not executed again until the  
        ' call to Last  
        Dim fileQuery2 = From file In fileQuery _  
                         Order By file.CreationTime _  
                         Select file.Name, file.CreationTime  
  
        ' Execute the query  
        Dim newestFile = fileQuery2.Last  
  
        Console.WriteLine("\r\nThe newest .txt file is {0}. Creation time: {1}", _  
                newestFile.Name, newestFile.CreationTime)  
  
        ' Keep the console window open in debug mode  
        Console.WriteLine("Press any key to exit.")  
        Console.ReadKey()  
  
    End Sub  
End Module

編譯程式碼

使用 System.Linq 命名空間的 Imports 陳述式，建立 Visual Basic 主控台應用程式專案。

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