Specifies how the operating system should open a file.
Assembly: mscorlib (in mscorlib.dll)
|Specifies that the operating system should create a new file. This requires FileIOPermissionAccess.Write. If the file already exists, an IOException is thrown.|
|Specifies that the operating system should create a new file. If the file already exists, it will be overwritten. This requires FileIOPermissionAccess.Write. System.IO.FileMode.Create is equivalent to requesting that if the file does not exist, use ; otherwise, use . If the file already exists but is a hidden file, an UnauthorizedAccessException is thrown.|
|Specifies that the operating system should open an existing file. The ability to open the file is dependent on the value specified by FileAccess. A System.IO.FileNotFoundException is thrown if the file does not exist.|
|Specifies that the operating system should open a file if it exists; otherwise, a new file should be created. If the file is opened with FileAccess.Read, FileIOPermissionAccess.Read is required. If the file access is FileAccess.Write then FileIOPermissionAccess.Write is required. If the file is opened with FileAccess.ReadWrite, both FileIOPermissionAccess.Read and FileIOPermissionAccess.Write are required. If the file access is FileAccess.Append, then FileIOPermissionAccess.Append is required.|
|Specifies that the operating system should open an existing file. Once opened, the file should be truncated so that its size is zero bytes. This requires FileIOPermissionAccess.Write. Attempts to read from a file opened with Truncate cause an exception.|
|Opens the file if it exists and seeks to the end of the file, or creates a new file. FileMode.Append can only be used in conjunction with FileAccess.Write. Attempting to seek to a position before the end of the file will throw an IOException and any attempt to read fails and throws an NotSupportedException.|
For an example of creating a file and writing text to a file, see How to: Write Text to a File. For an example of reading text from a file, see How to: Read Text from a File. For an example of reading from and writing to a binary file, see How to: Read and Write to a Newly Created Data File.
FileMode parameters control whether a file is overwritten, created, or opened, or some combination thereof. Use Open to open an existing file. To append to a file, use Append. To truncate a file or to create it if it does not exist, use Create.
Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows CE Platform Note: Windows CE cannot store more than 999 files in a directory when the files share the same short file name (that is, the eight-character name, period (.), and 3-character extension). The workaround is to ensure that the short file names are different. For example, if the files are named Longfilename0001.txt through Longfilename1000.txt, place the number at the beginning of the file name instead of at the end.
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.