FileInfo(String) コンストラクター

定義

名前空間:

System.IO

アセンブリ:

System.Runtime.dll

ソース:

FileInfo.cs

ファイル パスのラッパーとして機能する、FileInfo クラスの新しいインスタンスを初期化します。

public:
 FileInfo(System::String ^ fileName);

public FileInfo (string fileName);

new System.IO.FileInfo : string -> System.IO.FileInfo

Public Sub New (fileName As String)

パラメーター

fileName

String

新しいファイルの完全修飾名または相対ファイル名。 パスの末尾がディレクトリの区切り記号にならないようにしてください。

例外

ArgumentNullException

fileName が nullです。

SecurityException

呼び出し元に、必要なアクセス許可がありません。

ArgumentException

.NET Framework バージョンと .NET Core バージョンが 2.1 より前の場合: ファイル名が空であるか、空白だけが含まれているか、無効な文字が含まれています。

UnauthorizedAccessException

fileName へのアクセスが拒否されました

PathTooLongException

指定したパス、ファイル名、またはその両方がシステム定義の最大長を超えています。

NotSupportedException

fileName の文字列の途中にコロン (:) が含まれています。

例

次の例では、このコンストラクターを使用して 2 つのファイルを作成し、そのファイルを書き込み、読み取り、コピー、削除します。

using namespace System;
using namespace System::IO;

int main()
{
   String^ path = "c:\\MyTest.txt";
   FileInfo^ fi1 = gcnew FileInfo( path );
   if (  !fi1->Exists )
   {
      //Create a file to write to.
      StreamWriter^ sw = fi1->CreateText();
      try
      {
         sw->WriteLine( "Hello" );
         sw->WriteLine( "And" );
         sw->WriteLine( "Welcome" );
      }
      finally
      {
         if ( sw )
            delete (IDisposable^)sw;
      }
   }

   //Open the file to read from.
   StreamReader^ sr = fi1->OpenText();
   try
   {
      String^ s = "";
      while ( s = sr->ReadLine() )
      {
         Console::WriteLine( s );
      }
   }
   finally
   {
      if ( sr )
         delete (IDisposable^)sr;
   }

   try
   {
      String^ path2 = String::Concat( path, "temp" );
      FileInfo^ fi2 = gcnew FileInfo( path2 );
      
      //Ensure that the target does not exist.
      fi2->Delete();
      
      //Copy the file.
      fi1->CopyTo( path2 );
      Console::WriteLine( "{0} was copied to {1}.", path, path2 );
      
      //Delete the newly created file.
      fi2->Delete();
      Console::WriteLine( "{0} was successfully deleted.", path2 );
   }
   catch ( Exception^ e ) 
   {
      Console::WriteLine( "The process failed: {0}", e );
   }
}

//This code produces output similar to the following; 
//results may vary based on the computer/file structure/etc.:
//
//Hello
//And
//Welcome
//c:\MyTest.txt was copied to c:\MyTest.txttemp.
//c:\MyTest.txttemp was successfully deleted.

using System;
using System.IO;

class Test
{
    
    public static void Main()
    {
        string path = @"c:\temp\MyTest.txt";
        FileInfo fi1 = new FileInfo(path);

        if (!fi1.Exists)
        {
            //Create a file to write to.
            using (StreamWriter sw = fi1.CreateText())
            {
                sw.WriteLine("Hello");
                sw.WriteLine("And");
                sw.WriteLine("Welcome");
            }	
        }

        //Open the file to read from.
        using (StreamReader sr = fi1.OpenText())
        {
            string s = "";
            while ((s = sr.ReadLine()) != null)
            {
                Console.WriteLine(s);
            }
        }

        try
        {
            string path2 = path + "temp";
            FileInfo fi2 = new FileInfo(path2);

            //Ensure that the target does not exist.
            fi2.Delete();

            //Copy the file.
            fi1.CopyTo(path2);
            Console.WriteLine("{0} was copied to {1}.", path, path2);

            //Delete the newly created file.
            fi2.Delete();
            Console.WriteLine("{0} was successfully deleted.", path2);
        }
        catch (Exception e)
        {
            Console.WriteLine("The process failed: {0}", e.ToString());
        }
    }
}
//This code produces output similar to the following;
//results may vary based on the computer/file structure/etc.:
//
//Hello
//And
//Welcome
//c:\MyTest.txt was copied to c:\MyTest.txttemp.
//c:\MyTest.txttemp was successfully deleted.

Imports System.IO

Class Test

    Public Shared Sub Main()
        Dim path As String = "c:\temp\MyTest.txt"
        Dim fi1 As FileInfo = New FileInfo(path)

        If fi1.Exists = False Then
            'Create a file to write to.
            Dim sw As StreamWriter = fi1.CreateText()
            sw.WriteLine("Hello")
            sw.WriteLine("And")
            sw.WriteLine("Welcome")
            sw.Flush()
            sw.Close()
        End If

        'Open the file to read from.
        Dim sr As StreamReader = fi1.OpenText()

        Do While sr.Peek() >= 0
            Console.WriteLine(sr.ReadLine())
        Loop

        Try
            Dim path2 As String = path + "temp"
            Dim fi2 As FileInfo = New FileInfo(path2)

            'Ensure that the target does not exist.
            fi2.Delete()

            'Copy the file.
            fi1.CopyTo(path2)
            Console.WriteLine("{0} was copied to {1}.", path, path2)

            'Delete the newly created file.
            fi2.Delete()
            Console.WriteLine("{0} was successfully deleted.", path2)

        Catch e As Exception
            Console.WriteLine("The process failed: {0}", e.ToString())
        End Try
    End Sub
End Class
'This code produces output similar to the following; 
'results may vary based on the computer/file structure/etc.:
'
'Hello
'And
'Welcome
'c:\MyTest.txt was copied to c:\MyTest.txttemp.
'c:\MyTest.txttemp was successfully deleted.

次の例では、既存のファイルを開くか、ファイルを作成し、ファイルにテキストを追加して結果を表示します。

using namespace System;
using namespace System::IO;
int main()
{
   
   // Open an existing file, or create a new one.
   FileInfo^ fi = gcnew FileInfo( "temp.txt" );
   
   // Create a writer, ready to add entries to the file.
   StreamWriter^ sw = fi->AppendText();
   sw->WriteLine( "This is a new entry to add to the file" );
   sw->WriteLine( "This is yet another line to add..." );
   sw->Flush();
   sw->Close();
   
   // Get the information out of the file and display it.
   StreamReader^ sr = gcnew StreamReader( fi->OpenRead() );
   while ( sr->Peek() != -1 )
      Console::WriteLine( sr->ReadLine() );
}
//This code produces output similar to the following; 
//results may vary based on the computer/file structure/etc.:
//
//This is a new entry to add to the file
//This is yet another line to add...

using System;
using System.IO;

public class FileInfoMainTest
{
    public static void Main()
    {
        // Open an existing file, or create a new one.
        FileInfo fi = new FileInfo("temp.txt");
        // Create a writer, ready to add entries to the file.
        StreamWriter sw = fi.AppendText();
        sw.WriteLine("This is a new entry to add to the file");
        sw.WriteLine("This is yet another line to add...");
        sw.Flush();
        sw.Close();
        // Get the information out of the file and display it.
        StreamReader sr = new StreamReader( fi.OpenRead() );
        while (sr.Peek() != -1)
            Console.WriteLine( sr.ReadLine() );
    }
}
//This code produces output similar to the following;
//results may vary based on the computer/file structure/etc.:
//
//Add as many lines as you like...
//Add another line to the output...
//This is a new entry to add to the file
//This is yet another line to add...

Imports System.IO

Public Class FileInfoMainTest

    Public Shared Sub Main()
        ' Open an existing file, or create a new one.
        Dim fi As New FileInfo("temp.txt")
        ' Create a writer, ready to add entries to the file.
        Dim sw As StreamWriter = fi.AppendText()
        sw.WriteLine("This is a new entry to add to the file")
        sw.WriteLine("This is yet another line to add...")
        sw.Flush()
        sw.Close()
        Dim sr As New StreamReader(fi.OpenRead())
        ' Get the information out of the file and display it.
        While sr.Peek() <> -1
            Console.WriteLine(sr.ReadLine())
        End While
    End Sub
End Class
'This code produces output similar to the following; 
'results may vary based on the computer/file structure/etc.:
'
'This is a new entry to add to the file
'This is yet another line to add...

注釈

完全修飾ファイル名または相対ファイル名を指定できますが、セキュリティ チェックは完全修飾名を取得します。

こちらもご覧ください

• ファイルおよびストリーム入出力
• 方法: ファイルからのテキストの読み取り
• 方法: テキストのファイルへの書き込み