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FileStream.CanRead 屬性

定義

取得值,表示目前資料流是否支援讀取。

public:
 virtual property bool CanRead { bool get(); };
public override bool CanRead { get; }
member this.CanRead : bool
Public Overrides ReadOnly Property CanRead As Boolean

屬性值

如果資料流支援讀取,則為 true;如果資料流已關閉或以唯寫存取開啟,則為 false

範例

下列範例示範 屬性的使用 CanRead 。 此程式代碼的輸出為「無法寫入 MyFile.txt」。若要取得輸出訊息「MyFile.txt 可以寫入和讀取。」,請在建構函式中FileStreamFileAccess 參數變更為 ReadWrite

using namespace System;
using namespace System::IO;
int main( void )
{
   FileStream^ fs = gcnew FileStream( "MyFile.txt",FileMode::OpenOrCreate,FileAccess::Read );
   if ( fs->CanRead && fs->CanWrite )
   {
      Console::WriteLine( "MyFile.txt can be both written to and read from." );
   }
   else
   {
      Console::WriteLine( "MyFile.txt is not 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.Read);
        if (fs.CanRead && fs.CanWrite)
        {
            Console.WriteLine("MyFile.txt can be both written to and read from.");
        }
        else if (fs.CanRead)
        {
            Console.WriteLine("MyFile.txt is not writable.");
        }
    }
}
open System.IO

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

if fs.CanRead && fs.CanWrite then
    printfn "MyFile.txt can be both written to and read from."
else if fs.CanRead then
    printfn "MyFile.txt is not writable."
Imports System.IO

Class TestRW

    Public Shared Sub Main()
        Dim fs As New FileStream("MyFile.txt", FileMode.OpenOrCreate, FileAccess.Read)
        If fs.CanRead And fs.CanWrite Then
            Console.WriteLine("MyFile.txt can be both written to and read from.")
        Else
            If fs.CanRead Then
                Console.WriteLine("MyFile.txt is not writable.")
            End If
        End If
    End Sub
End Class

備註

如果衍生自 Stream 的類別不支援讀取, 則呼叫、 ReadByteBeginRead 方法會Read擲回 NotSupportedException

如果資料流已關閉,這個屬性會傳 false回 。

適用於

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