basic_ofstream

basic_ofstreambasic_ostreambasic_iosios_base

• Data Type and Member Function Indexes
• Synopsis
• Description
• Interface
• Types
• Constructors
• Destructor
• Member Functions
• Examples
• See Also
• Standards Conformance

Data Types
char_type int_type ios_type off_type	ofstream pos_type traits_type wofstream

Member Functions

close() is_open() open() rdbuf()

#include <fstream> 
template<class charT, class traits = char_traits<charT> >
class basic_ofstream
: public basic_ostream<charT, traits>

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.

template<class charT, class traits = char_traits<charT> >
class basic_ofstream
: public basic_ostream<charT, traits> {

 public:

  typedef basic_ios<charT, traits>    ios_type;

  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;

  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();

};

char_type

The type char_type is a synonym for the template parameter 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 parameter traits.

wofstream

The type wofstream is an instantiation of class basic_ofstream on type wchar_t:

typedef basic_ofstream<wchar_t> wofstream;

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 at 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 provided 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 permission.

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 provided 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 provided 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.

virtual ~basic_ofstream();

Destroys an object of class basic_ofstream.

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 return 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 opening 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 provided 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 permission.

basic_filebuf<charT,traits>* 
rdbuf() const;

Returns a pointer to the basic_filebuf associated with the stream.

See basic_fstream, basic_ifstream and basic_filebuf examples.

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

ANSI X3J16/ISO WG21 Joint C++ Committee

©Copyright 1996, Rogue Wave Software, Inc.