FileInfo::Open Method (FileMode)

.NET Framework (current version)

Opens a file in the specified mode.

Namespace: System.IO
Assembly: mscorlib (in mscorlib.dll)

Syntax

public:
FileStream^ Open(
	FileMode mode
)

Parameters

mode: Type: System.IO::FileMode
A FileMode constant specifying the mode (for example, Open or Append) in which to open the file.

Return Value

Type: System.IO::FileStream^

A file opened in the specified mode, with read/write access and unshared.

Exceptions

Exception	Condition
FileNotFoundException	The file is not found.
UnauthorizedAccessException	The file is read-only or is a directory.
DirectoryNotFoundException	The specified path is invalid, such as being on an unmapped drive.
IOException	The file is already open.

Examples

The following example opens a file, adds some information to the file, and reads the file.

C++

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

int main()
{
   String^ path = "c:\\MyTest.txt";
   FileInfo^ fi = gcnew FileInfo( path );

   // Delete the file if it exists.
   if (  !fi->Exists )
   {
      //Create the file.
      FileStream^ fs = fi->Create();
      try
      {
         array<Byte>^info = (gcnew UTF8Encoding( true ))->GetBytes( "This is some text in the file." );

         //Add some information to the file.
         fs->Write( info, 0, info->Length );
      }
      finally
      {
         if ( fs )
            delete (IDisposable^)fs;
      }
   }

   //Open the stream and read it back.
   FileStream^ fs = fi->Open( FileMode::Open );
   try
   {
      array<Byte>^b = gcnew array<Byte>(1024);
      UTF8Encoding^ temp = gcnew UTF8Encoding( true );
      while ( fs->Read( b, 0, b->Length ) > 0 )
      {
         Console::WriteLine( temp->GetString( b ) );
      }
   }
   finally
   {
      if ( fs )
         delete (IDisposable^)fs;
   }
}

//This code produces output similar to the following; 
//results may vary based on the computer/file structure/etc.:
//
//This is some text in the file.
//
//
//
//
//
//
//
//
//
//
//
//
//

Security

FileIOPermission

for writing to and reading from files. Associated enumerations: FileIOPermissionAccess::Write and FileIOPermissionAccess::Read

Version Information

Universal Windows Platform
Available since 10
.NET Framework
Available since 1.1
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0