Directory.Exists(String) Metodo

Definizione

Spazio dei nomi:

System.IO

Assembly:

System.Runtime.dll

Origine:

Directory.cs

Determina se il percorso specificato fa riferimento a una directory esistente sul disco.

public:
 static bool Exists(System::String ^ path);

public static bool Exists (string? path);

static member Exists : string -> bool

Public Shared Function Exists (path As String) As Boolean

Parametri

path

String

Percorso da testare.

Restituisce

Boolean

true se path fa riferimento a una directory esistente; false se la directory non esiste o si verifica un errore durante il tentativo di determinare se la directory specificata esiste.

Esempio

L'esempio seguente accetta una matrice di nomi di file o directory nella riga di comando, determina il tipo di nome e lo elabora in modo appropriato.

// For File::Exists, Directory::Exists
using namespace System;
using namespace System::IO;
using namespace System::Collections;

// Insert logic for processing found files here.
void ProcessFile( String^ path )
{
   Console::WriteLine( "Processed file '{0}'.", path );
}


// Process all files in the directory passed in, recurse on any directories 
// that are found, and process the files they contain.
void ProcessDirectory( String^ targetDirectory )
{
   
   // Process the list of files found in the directory.
   array<String^>^fileEntries = Directory::GetFiles( targetDirectory );
   IEnumerator^ files = fileEntries->GetEnumerator();
   while ( files->MoveNext() )
   {
      String^ fileName = safe_cast<String^>(files->Current);
      ProcessFile( fileName );
   }

   
   // Recurse into subdirectories of this directory.
   array<String^>^subdirectoryEntries = Directory::GetDirectories( targetDirectory );
   IEnumerator^ dirs = subdirectoryEntries->GetEnumerator();
   while ( dirs->MoveNext() )
   {
      String^ subdirectory = safe_cast<String^>(dirs->Current);
      ProcessDirectory( subdirectory );
   }
}

int main( int argc, char *argv[] )
{
   for ( int i = 1; i < argc; i++ )
   {
      String^ path = gcnew String(argv[ i ]);
      if ( File::Exists( path ) )
      {
         
         // This path is a file
         ProcessFile( path );
      }
      else
      if ( Directory::Exists( path ) )
      {
         
         // This path is a directory
         ProcessDirectory( path );
      }
      else
      {
         Console::WriteLine( "{0} is not a valid file or directory.", path );
      }

   }
}

// For File.Exists, Directory.Exists
using System;
using System.IO;
using System.Collections;

public class RecursiveFileProcessor
{
    public static void Main(string[] args)
    {
        foreach(string path in args)
        {
            if(File.Exists(path))
            {
                // This path is a file
                ProcessFile(path);
            }
            else if(Directory.Exists(path))
            {
                // This path is a directory
                ProcessDirectory(path);
            }
            else
            {
                Console.WriteLine("{0} is not a valid file or directory.", path);
            }
        }
    }

    // Process all files in the directory passed in, recurse on any directories
    // that are found, and process the files they contain.
    public static void ProcessDirectory(string targetDirectory)
    {
        // Process the list of files found in the directory.
        string [] fileEntries = Directory.GetFiles(targetDirectory);
        foreach(string fileName in fileEntries)
            ProcessFile(fileName);

        // Recurse into subdirectories of this directory.
        string [] subdirectoryEntries = Directory.GetDirectories(targetDirectory);
        foreach(string subdirectory in subdirectoryEntries)
            ProcessDirectory(subdirectory);
    }

    // Insert logic for processing found files here.
    public static void ProcessFile(string path)
    {
        Console.WriteLine("Processed file '{0}'.", path);	
    }
}

module RecursiveFileProcessor

open System.IO

// Insert logic for processing found files here.
let processFile path =
    printfn $"Processed file '%s{path}'."

// Process all files in the directory passed in, recurse on any directories
// that are found, and process the files they contain.
let rec processDirectory targetDirectory =
    // Process the list of files found in the directory.
    let fileEntries = Directory.GetFiles targetDirectory
    for fileName in fileEntries do
        processFile fileName

    // Recurse into subdirectories of this directory.
    let subdirectoryEntries = Directory.GetDirectories targetDirectory
    for subdirectory in subdirectoryEntries do
        processDirectory subdirectory

[<EntryPoint>]
let main args =
    for path in args do
        if File.Exists path then
            // This path is a file
            processFile path
        elif Directory.Exists path then
            // This path is a directory
            processDirectory path
        else
            printfn $"{path} is not a valid file or directory."
    0

' For File.Exists, Directory.Exists 

Imports System.IO
Imports System.Collections

Public Class RecursiveFileProcessor

    Public Overloads Shared Sub Main(ByVal args() As String)
        Dim path As String
        For Each path In args
            If File.Exists(path) Then
                ' This path is a file.
                ProcessFile(path)
            Else
                If Directory.Exists(path) Then
                    ' This path is a directory.
                    ProcessDirectory(path)
                Else
                    Console.WriteLine("{0} is not a valid file or directory.", path)
                End If
            End If
        Next path
    End Sub


    ' Process all files in the directory passed in, recurse on any directories 
    ' that are found, and process the files they contain.
    Public Shared Sub ProcessDirectory(ByVal targetDirectory As String)
        Dim fileEntries As String() = Directory.GetFiles(targetDirectory)
        ' Process the list of files found in the directory.
        Dim fileName As String
        For Each fileName In fileEntries
            ProcessFile(fileName)

        Next fileName
        Dim subdirectoryEntries As String() = Directory.GetDirectories(targetDirectory)
        ' Recurse into subdirectories of this directory.
        Dim subdirectory As String
        For Each subdirectory In subdirectoryEntries
            ProcessDirectory(subdirectory)
        Next subdirectory

    End Sub

    ' Insert logic for processing found files here.
    Public Shared Sub ProcessFile(ByVal path As String)
        Console.WriteLine("Processed file '{0}'.", path)
    End Sub
End Class

Commenti

Il path parametro è autorizzato a specificare informazioni relative o assolute sul percorso. Le informazioni relative sul percorso sono interpretate come relative alla directory di lavoro corrente.

Gli spazi finali vengono rimossi dalla fine del path parametro prima di verificare se la directory esiste.

La distinzione tra maiuscole e minuscole del path parametro corrisponde a quella del file system in cui è in esecuzione il codice. Ad esempio, non fa distinzione tra maiuscole e minuscole in NTFS (file system Windows predefinito) e fa distinzione tra maiuscole e minuscole nei file system Linux.

Se non si dispone almeno dell'autorizzazione di sola lettura per la directory, il Exists metodo restituirà false.

Il Exists metodo restituisce false se si verifica un errore durante il tentativo di determinare se il file specificato esiste. Questa situazione può verificarsi in situazioni che generano eccezioni, ad esempio il passaggio di un nome file con caratteri non validi o troppi caratteri, un errore o un disco mancante o se il chiamante non dispone dell'autorizzazione per leggere il file.

Vedi anche

• DirectoryInfo
• I/O di file e Stream
• Procedura: Leggere testo da un file
• Procedura: Scrivere un testo in un file