Standard C++ Library
Copyright 1998, Rogue Wave Software, Inc.
NAME
basic_ofstream, ofstream, wofstream
- Supports writing into named files or other devices asso-
ciated with a file descriptor.
SYNOPSIS
#include <fstream>
template<class charT, class traits = char_traits<charT> >
class basic_ofstream
: public basic_ostream<charT, traits>
DESCRIPTION
The template class basic_ofstream<charT,traits> supports
writing into named files or other devices associated with a
file descriptor. It uses a basic_filebuf object to control
the associated sequences. It inherits from basic_ostream and
can therefore use all the formatted and unformatted output
functions.
INTERFACE
template<class charT, class traits = char_traits<charT> >
class basic_ofstream
: public basic_ostream<charT, traits> {
public:
typedef charT char_type;
typedef traits traits_type;
typedef typename traits::int_type int_type;
typedef typename traits::pos_type pos_type;
typedef typename traits::off_type off_type;
typedef basic_ios<charT, traits> ios_type;
basic_ofstream();
explicit basic_ofstream(const char *s,
ios_base::openmode mode =
ios_base::out,
long protection = 0666);
explicit basic_ofstream(int fd);
basic_ofstream(int fd, char_type* buf, int len);
virtual ~basic_ofstream();
basic_filebuf<charT, traits> *rdbuf() const;
bool is_open();
void open(const char *s, ios_base::openmode mode =
ios_type::out, long protection = 0666);
void close();
};
TYPES
char_type
The type char_type is a synonym for the template parame-
ter charT.
off_type
The type off_type is a synonym of type traits::off_type.
ofstream
The type ofstream is an instantiation of class
basic_ofstream on type char:
typedef basic_ofstream<char> ofstream;
int_type
The type int_type is a synonym of type traits::in_type.
ios_type
The type ios_type is an instantiation of class basic_ios
on type charT.
pos_type
The type pos_type is a synonym of type traits::pos_type.
traits_type
The type traits_type is a synonym for the template param-
eter traits.
wofstream
The type wofstream is an instantiation of class
basic_ofstream on type wchar_t:
typedef basic_ofstream<wchar_t> wofstream;
CONSTRUCTORS
basic_ofstream();
Constructs an object of class
basic_ofstream<charT,traits>, initializing the base class
basic_ostream with the associated file buffer, which is
initialized by calling the basic_filebuf constructor
basic_filebuf<charT,traits>(). After construction a file
can be attached to the basic_ofstream_object using the
open member function.
basic_ofstream(const char* s,
ios_base::openmode mode= ios_base::in,
long protection= 0666);
Constructs an object of class
basic_ofstream<charT,traits>, initializing the base class
basic_ostream with the associated file buffer, which is
initialized by calling the basic_filebuf constructor
basic_filebuf<charT,traits>(). The constructor then calls
the open function open(s,mode,protection) in order to
attach the file whose name is pointed to by s, to the
basic_ofstream object. The third argument, protection, is
used as the file permissions. It does not appear in the
Standard C++ description and is included as an extension.
It determines the file read/write/execute permissions
under UNIX. It is more limited under DOS since files are
always readable and do not have special execute permis-
sion.
explicit basic_ofstream(int fd);
Constructs an object of class
basic_ofstream<charT,traits>, initializing the base class
basic_ostream with the associated file buffer, which is
initialized by calling the basic_filebuf constructor
basic_filebuf<charT,traits>(). The constructor then calls
the basic_filebuf open function open(fd) in order to
attach the file descriptor fd to the basic_ofstream
object. This constructor is not described in the C++
standard, and is included as an extension in order to
manipulate pipes, sockets, or other UNIX devices that can
be accessed through file descriptors. If the function
fails, it sets ios_base::failbit.
basic_ofstream(int fd, char_type* buf,int len);
Constructs an object of class
basic_ofstream<charT,traits>, initializing the base class
basic_ostream with the associated file buffer, which is
initialized by calling the basic_filebuf constructor
basic_filebuf<charT,traits>(). The constructor then calls
the basic_filebuf open function open(fd) in order to
attach the file descriptor fd to the basic_ofstream
object. The underlying buffer is then replaced by calling
the basic_filebuf member function setbuf with parameters
buf and len. This constructor is not described in the C++
standard, and is included as an extension in order to
manipulate pipes, sockets, or other UNIX devices that can
be accessed through file descriptors. It also maintains
compatibility with the old iostreams library. If the
function fails, it sets ios_base::failbit.
DESTRUCTORS
virtual ~basic_ofstream();
Destroys an object of class basic_ofstream.
MEMBER FUNCTIONS
void
close();
Calls the associated basic_filebuf function close() and
if this function fails, it calls the basic_ios member
function setstate(failbit).
bool
is_open();
Calls the associated basic_filebuf function is_open() and
returns its result.
void
open(const char* s,ios_base::openmode =
ios_base::out, long protection = 0666);
Calls the associated basic_filebuf function
open(s,mode,protection) and, if this function fails open-
ing the file, calls the basic_ios member function
setstate(failbit). The third argument, protection, is
used as the file permissions. It does not appear in the
Standard C++ description and is included as an extension.
It determines the file read/write/execute permissions
under UNIX, and is more limited under DOS since files are
always readable and do not have special execute permis-
sion.
basic_filebuf<charT,traits>*
rdbuf() const;
Returns a pointer to the basic_filebuf associated with
the stream.
EXAMPLE
See basic_fstream, basic_ifstream and basic_filebuf exam-
ples.
SEE ALSO
char_traits(3C++), ios_base(3C++), basic_ios(3C++),
basic_filebuf(3C++), basic_ifstream(3C++),
basic_fstream(3C++)
Working Paper for Draft Proposed International Standard for
Information Systems--Programming Language C++, Section
27.8.1.8
STANDARDS CONFORMANCE
ANSI X3J16/ISO WG21 Joint C++ Committee