CFile::CFile
CFile();
CFile(inthFile**);**
CFile(LPCTSTRlpszFileName**,UINTnOpenFlags);**
throw(CFileException);
Parameters
hFile
The handle of a file that is already open.
lpszFileName
A string that is the path to the desired file. The path can be relative or absolute.
nOpenFlags
Sharing and access mode. Specifies the action to take when opening the file. You can combine options listed below by using the bitwise-OR (|) operator. One access permission and one share option are required; the modeCreate and modeNoInherit modes are optional. The values are as follows:
CFile::modeCreate Directs the constructor to create a new file. If the file exists already, it is truncated to 0 length.
CFile::modeNoTruncate Combine this value with modeCreate. If the file being created already exists, it is not truncated to 0 length. Thus the file is guaranteed to open, either as a newly created file or as an existing file. This might be useful, for example, when opening a settings file that may or may not exist already. This option applies to CStdioFile as well.
CFile::modeRead Opens the file for reading only.
CFile::modeReadWrite Opens the file for reading and writing.
CFile::modeWrite Opens the file for writing only.
CFile::modeNoInherit Prevents the file from being inherited by child processes.
CFile::shareDenyNone Opens the file without denying other processes read or write access to the file. Create fails if the file has been opened in compatibility mode by any other process.
CFile::shareDenyRead Opens the file and denies other processes read access to the file. Create fails if the file has been opened in compatibility mode or for read access by any other process.
CFile::shareDenyWrite Opens the file and denies other processes write access to the file. Create fails if the file has been opened in compatibility mode or for write access by any other process.
CFile::shareExclusive Opens the file with exclusive mode, denying other processes both read and write access to the file. Construction fails if the file has been opened in any other mode for read or write access, even by the current process.
CFile::shareCompat This flag is not available in 32 bit MFC. This flag maps to CFile::shareExclusive when used in CFile::Open.
CFile::typeText Sets text mode with special processing for carriage return–linefeed pairs (used in derived classes only).
CFile::typeBinary Sets binary mode (used in derived classes only).
Remarks
The default constructor does not open a file but rather sets m_hFile to CFile::hFileNull. Because this constructor does not throw an exception, it does not make sense to use TRY/CATCH logic. Use the Open member function, then test directly for exception conditions. For a discussion of exception-processing strategy, see the article in Visual C++ Programmer's Guide.
The constructor with one argument creates a CFile object that corresponds to an existing operating-system file identified by hFile. No check is made on the access mode or file type. When the CFile object is destroyed, the operating-system file will not be closed. You must close the file yourself.
The constructor with two arguments creates a CFile object and opens the corresponding operating-system file with the given path. This constructor combines the functions of the first constructor and the Open member function. It throws an exception if there is an error while opening the file. Generally, this means that the error is unrecoverable and that the user should be alerted.
Example
For an example using the default constructor, see CFile::Open. For an example using the constructor which throws exceptions, see CATCH.
The HANDLE constructor can be used as in the following code, which creates a file named C:\FOO.DAT and writes the ANSI characters "Hockey is best!":
HANDLE hFile = CreateFile(_T("C:\\FOO.DAT"),
GENERIC_WRITE, FILE_SHARE_READ,
NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
if (hFile == INVALID_HANDLE_VALUE)
AfxMessageBox(_T("Couldn't create the file!"));
else
{
// Attach a CFile object to the handle we have.
CFile myFile(hFile);
static const char sz[] = "Hockey is best!";
// write string, without null-terminator
myFile.Write(sz, lstrlen(sz));
// We can call Close() explicitly, but the destructor would have
// also closed the file for us. Note that there's no need to
// call the CloseHandle() on the handle returned by the API because
// MFC will close it for us.
myFile.Close();
}