Stream.CanWrite 屬性

定義

命名空間:

System.IO

組件:

System.Runtime.dll

來源:

Stream.cs

在衍生類別中覆寫時，取得指示目前資料流是否支援寫入的數值。

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

public abstract bool CanWrite { get; }

member this.CanWrite : bool

Public MustOverride ReadOnly Property CanWrite As Boolean

屬性值

Boolean

如果資料流支援寫入，則為 true；否則，為 false。

範例

以下是使用 屬性的 CanWrite 範例。

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.

備註

如果衍生自 Stream 的類別不支援寫入， 則呼叫 Write、 BeginWrite或 WriteByte 會 NotSupportedException擲回 。 在這種情況下， Flush 通常會實作為空的方法，以確保與其他 Stream 類型完全相容，因為排清只讀數據流是有效的。

另請參閱

• 檔案和資料流 I/O
• 作法：讀取檔案中的文字
• 作法：將文字寫入檔案