FileStream.CanWrite Propriedade
Importante
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Obtém um valor que indica se o fluxo atual dá suporte a gravação.
public:
virtual property bool CanWrite { bool get(); };
public override bool CanWrite { get; }
member this.CanWrite : bool
Public Overrides ReadOnly Property CanWrite As Boolean
true
se o fluxo der suporte à gravação; false
se o fluxo estiver fechado ou tiver sido aberto com acesso somente leitura.
O exemplo a seguir usa a CanWrite
propriedade para marcar se um fluxo dá suporte à gravação.
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
Veja a seguir um exemplo usando a CanWrite
propriedade . A saída desse código é "MyFile.txt é gravável". Para obter a mensagem de saída "MyFile.txt pode ser gravado e lido.", altere o FileAccess
parâmetro para ReadWrite
no FileStream
construtor.
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
Se uma classe derivada de não der Stream suporte à gravação, uma chamada para SetLength, Write, BeginWriteou WriteByte gerará um NotSupportedException.
Se o fluxo for fechado, essa propriedade retornará false
.
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