Stream.CanWrite Właściwość

Definicja

Gdy jest zastępowany w klasie pochodnej, pobiera wartość wskazującą, czy bieżący strumień obsługuje zapisywanie.When overridden in a derived class, gets a value indicating whether the current stream supports writing.

public:
 abstract property bool CanWrite { bool get(); };
public abstract bool CanWrite { get; }
member this.CanWrite : bool
Public MustOverride ReadOnly Property CanWrite As Boolean

Wartość właściwości

trueJeśli strumień obsługuje zapis; w przeciwnym razie. falsetrue if the stream supports writing; otherwise, false.

Przykłady

Poniżej przedstawiono przykład użycia CanWrite właściwości.The following is an example of using the CanWrite property.

using namespace System;
using namespace System::IO;
int main()
{
   FileStream^ fs = gcnew FileStream( "MyFile.txt",FileMode::OpenOrCreate,FileAccess::Write );
   if ( fs->CanRead && fs->CanWrite )
   {
      Console::WriteLine( "MyFile.txt can be both written to and read from." );
   }
   else
   if ( fs->CanWrite )
   {
      Console::WriteLine( "MyFile.txt is writable." );
   }
}

//This code outputs "MyFile.txt is writable."
//To get the output message "MyFile.txt can be both written to and read from.",
//change the FileAccess parameter to ReadWrite in the FileStream constructor.
using System;
using System.IO;

class TestRW 
{
  public static void Main(String[] args)
  { 
    FileStream fs = new FileStream("MyFile.txt", FileMode.OpenOrCreate,
       FileAccess.Write);
    if (fs.CanRead && fs.CanWrite) {
        Console.WriteLine("MyFile.txt can be both written to and read from.");
    }
    else if (fs.CanWrite) {
        Console.WriteLine("MyFile.txt is writable.");
    }
  }
}
//This code outputs "MyFile.txt is writable."
//To get the output message "MyFile.txt can be both written to and read from.",
//change the FileAccess parameter to ReadWrite in the FileStream constructor.
Imports System.IO

Class TestRW    

    Public Shared Sub Main()
        Dim fs As New FileStream("MyFile.txt", FileMode.OpenOrCreate, _
           FileAccess.Write)
        If fs.CanRead And fs.CanWrite Then
            Console.WriteLine("MyFile.txt can be both written to and read from.")
        Else
            If fs.CanWrite Then
                Console.WriteLine("MyFile.txt is writable.")
            End If
        End If
    End Sub
End Class

'This code outputs "MyFile.txt is writable."
'To get the output message "MyFile.txt can be both written to and read from.",
'change the FileAccess parameter to ReadWrite in the FileStream constructor.

Uwagi

Jeśli Stream Klasa pochodna nie obsługuje pisania, wywołanie do NotSupportedException Write, BeginWritelub WriteByte zgłasza.If a class derived from Stream does not support writing, a call to Write, BeginWrite, or WriteByte throws a NotSupportedException. W takich przypadkach jest Flush zwykle implementowana jako pusta Metoda w celu zapewnienia pełnej zgodności z innymi Stream typami, ponieważ jest ona prawidłowa do opróżniania strumienia tylko do odczytu.In such cases, Flush is typically implemented as an empty method to ensure full compatibility with other Stream types since it's valid to flush a read-only stream.

Jeśli strumień jest zamknięty, ta właściwość zwraca wartość false.If the stream is closed, this property returns false.

Dotyczy

Zobacz też