FileStream.CanWrite Propiedad

Definición

Espacio de nombres:

System.IO

Ensamblado:

System.Runtime.dll

Source:

FileStream.cs

Obtiene un valor que indica si la secuencia actual admite escritura.

public:
 virtual property bool CanWrite { bool get(); };

public override bool CanWrite { get; }

member this.CanWrite : bool

Public Overrides ReadOnly Property CanWrite As Boolean

Valor de propiedad

Boolean

Es true si la secuencia admite escritura; es false si la secuencia está cerrada o se abrió con acceso de solo lectura.

Ejemplos

En el ejemplo siguiente se usa la CanWrite propiedad para comprobar si una secuencia admite la escritura.

using namespace System;
using namespace System::IO;
using namespace System::Text;

int main()
{
   String^ path = "c:\\temp\\MyTest.txt";
   
   // Ensure that the file is readonly.
   File::SetAttributes( path, static_cast<FileAttributes>(File::GetAttributes( path ) | FileAttributes::ReadOnly) );
   
   //Create the file.
   FileStream^ fs = gcnew FileStream( path,FileMode::OpenOrCreate,FileAccess::Read );
   try
   {
      if ( fs->CanWrite )
      {
         Console::WriteLine( "The stream for file {0} is writable.", path );
      }
      else
      {
         Console::WriteLine( "The stream for file {0} is not writable.", path );
      }
   }
   finally
   {
      if ( fs )
         delete (IDisposable^)fs;
   }
}

using System;
using System.IO;
using System.Text;

class Test
{
    
    public static void Main()
    {
        string path = @"c:\temp\MyTest.txt";

        // Ensure that the file is readonly.
        File.SetAttributes(path, File.GetAttributes(path) | FileAttributes.ReadOnly);

        //Create the file.
        using (FileStream fs = new FileStream (path, FileMode.OpenOrCreate, FileAccess.Read))
        {
            if (fs.CanWrite)
            {
                Console.WriteLine("The stream for file {0} is writable.", path);
            }
            else
            {
                Console.WriteLine("The stream for file {0} is not writable.", path);
            }
        }
    }
}

open System.IO

let path = @"c:\temp\MyTest.txt"

// Ensure that the file is readonly.
File.SetAttributes(path, File.GetAttributes path ||| FileAttributes.ReadOnly)

//Create the file.
do
    use fs = new FileStream(path, FileMode.OpenOrCreate, FileAccess.Read)

    if fs.CanWrite then
        printfn $"The stream for file {path} is writable."

    else
        printfn $"The stream for file {path} is not writable."

Imports System.IO

Public Class Test

    Public Shared Sub Main()
        Dim path As String = "c:\temp\MyTest.txt"

        'Ensure that the file is readonly.
        File.SetAttributes(path, File.GetAttributes(path) Or FileAttributes.ReadOnly)

        'Create the file.
        Dim fs As FileStream = New FileStream(path, FileMode.OpenOrCreate, FileAccess.Read)

        If fs.CanWrite Then
            Console.WriteLine("The stream connected to {0} is writable.", path)
        Else
            Console.WriteLine("The stream connected to {0} is not writable.", path)
        End If
        fs.Close()
    End Sub
End Class

A continuación se muestra un ejemplo mediante la CanWrite propiedad . La salida de este código es "MyFile.txt se puede escribir". Para obtener el mensaje de salida "MyFile.txt se puede escribir en y leer desde.", cambie el FileAccess parámetro a ReadWrite en el FileStream constructor .

using namespace System;
using namespace System::IO;
int main( void )
{
   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
   {
      Console::WriteLine( "MyFile.txt is writable." );
   }

   return 0;
}

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.");
        }
    }
}

open System.IO

let fs = new FileStream("MyFile.txt", FileMode.OpenOrCreate, FileAccess.Write)

if fs.CanRead && fs.CanWrite then
    printfn "MyFile.txt can be both written to and read from."
elif fs.CanWrite then
    printfn "MyFile.txt is writable."

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.")
        ElseIf fs.CanWrite Then
            Console.WriteLine("MyFile.txt is writable.")
        End If
    End Sub
End Class

Comentarios

Si una clase derivada de Stream no admite la escritura, una llamada a SetLength, Write, BeginWriteo WriteByte produce una NotSupportedExceptionexcepción .

Si se cierra la secuencia, esta propiedad devuelve false.

Consulte también

• E/S de archivos y secuencias
• Cómo: Leer texto de un archivo
• Cómo: Escribir texto en un archivo