basic_ios (3C++std) - Tru64 UNIX
Standard C++ LibraryCopyright 1996, Rogue Wave Software, Inc.
NAME
basic_ios,ios
This page describes the ANSI ios class. If you would like information on
the pre-ANSI ios class, use the command:
man 3C++ ios or man ios.3C++
SYNOPSIS
#include <ios>
template<class charT, class traits = char_traits<charT> >
class basic_ios : public ios_base
DESCRIPTION
The class basic_ios is a base class that provides the common functionality
required by all streams. It maintains state information that reflects the
integrity of the stream and stream buffer. It also maintains the link
between the stream classes and the stream buffers classes via the rdbuf
member functions. Classes derived from basic_ios specialize operations for
input, and output.
INTERFACE
template<class charT, class traits = char_traits<charT> >
class basic_ios : public ios_base {
public:
typedef basic_ios<charT, traits> ios_type;
typedef basic_streambuf<charT, traits> streambuf_type;
typedef basic_ostream<charT, traits> ostream_type;
typedef typename traits::char_type char_type;
typedef traits traits_type;
typedef typename traits::int_type int_type;
typedef typename traits::off_type off_type;
typedef typename traits::pos_type pos_type;
explicit basic_ios(basic_streambuf<charT, traits> *sb_arg);
virtual ~basic_ios();
char_type fill() const;
char_type fill(char_type ch);
void exceptions(iostate except);
iostate exceptions() const;
void clear(iostate state = goodbit);
void setstate(iostate state);
iostate rdstate() const;
operator void*() const;
bool operator!() const;
bool good() const;
bool eof() const;
bool fail() const;
bool bad() const;
ios_type& copyfmt(const ios_type& rhs);
ostream_type *tie() const;
ostream_type *tie(ostream_type *tie_arg);
streambuf_type *rdbuf() const;
streambuf_type *rdbuf( streambuf_type *sb);
locale imbue(const locale& loc);
char narrow(charT, char) const;
charT widen(char) const;
protected:
basic_ios();
void init(basic_streambuf<charT, traits> *sb);
};
TYPES
char_type
The type char_type is a synonym of type traits::char_type.
ios
The type ios is an instantiation of basic_ios on char:
typedef basic_ios<char> ios;
int_type
The type int_type is a synonym of type traits::in_type.
ios_type
The type ios_type is a synonym for basic_ios<charT, traits> .
off_type
The type off_type is a synonym of type traits::off_type.
ostream_type
The type ostream_type is a synonym for basic_ostream<charT, traits> .
pos_type
The type pos_type is a synonym of type traits::pos_type.
streambuf_type
The type streambuf_type is a synonym for basic_streambuf<charT, traits>
.
traits_type
The type traits_type is a synonym for the template parameter traits.
wios
The type wios is an instantiation of basic_ios on wchar_t:
typedef basic_ios<wchar_t> wios;
PUBLIC CONSTRUCTORS
explicit basic_ios(basic_streambuf<charT, traits>* sb);
Constructs an object of class basic_ios, assigning initial values to its
member objects by calling init(sb). If sb is a null pointer, the stream
is positioned in error state, by triggering its badbit.
basic_ios();
Constructs an object of class basic_ios leaving its member objects
uninitialized. The object must be initialized by calling the init member
function before using it.
PUBLIC DESTRUCTOR
virtual ~basic_ios();
Destroys an object of class basic_ios.
PUBLIC MEMBER FUNCTIONS
bool
bad() const;
Returns true if badbit is set in rdstate().
void
clear(iostate state = goodbit);
If (state & exception()) == 0, returns. Otherwise, the function throws
an object of class ios_base::failure. After the call returns state ==
rdstate().
basic_ios&
copyfmt(const basic_ios& rhs);
Assigns to the member objects of *this the corresponding member objects
of rhs, with the following exceptions:
• rdstate() and rdbuf() are left unchanged
• calls ios_base::copyfmt
• exceptions() is altered last by calling
exceptions(rhs.exceptions())
bool
eof() const;
Returns true if eofbit is set in rdstate().
iostate
exceptions() const;
Returns a mask that determines what elements set in rdstate() cause
exceptions to be thrown.
void
exceptions(iostate except);
Set the exception mask to except then calls clear(rdstate()).
bool
fail() const;
Returns true if failbit or badbit is set in rdstate().
char_type
fill() const;
Returns the character used to pad (fill) an output conversion to the
specified field width.
char_type
fill(char_type fillch);
Saves the field width value then replaces it by fillch and returns the
previously saved value.
bool
good() const;
Returns rdstate() == 0.
locale
imbue(const locale& loc);
Saves the value returned by getloc() then assigns loc to a private
variable and if rdbuf() != 0 calls rdbuf()->pubimbue(loc) and returns
the previously saved value.
void
init(basic_streambuf<charT,traits>* sb);
Performs the following initialization:
rdbuf() sb
tie() 0
rdstate() goodbit if sb is not null otherwise badbit
exceptions() goodbit
flags() skipws | dec
width() 0
precision() 6
fill() the space character
getloc() locale::locale()
char
narrow(charT c, char dfault) const;
Uses the stream's locale to convert the wide character c to a tiny
character, and then returns it. If no conversion exists, it returns the
character dfault.
bool
operator!() const;
Returns fail() ? 1 : 0;
streambuf_type*
rdbuf() const;
Returns a pointer to the stream buffer associated with the stream.
streambuf_type*
rdbuf(streambuf_type* sb);
Associates a stream buffer with the stream. All the input and output
will be directed to this stream buffer. If sb is a null pointer, the
stream is positioned in error state, by triggering its badbit.
iostate
rdstate() const;
Returns the control state of the stream.
void
setstate(iostate state);
Calls clear(rdstate() | state).
ostream_type*
tie() const;
Returns an output sequence that is tied to (synchronized with) the
sequence controlled by the stream buffer.
ostream_type*
tie(ostream_type* tiestr);
Saves the tie() value then replaces it by tiestr and returns the value
previously saved.
operator
void*() const;
Returns fail() ? 0 : 1;
charT
widen(char c) const;
Uses the stream's locale to convert the tiny character c to a wide
character, then returns it.
SEE ALSO
ios_base(3C++std), basic_istream(3C++std), basic_ostream(3C++std),
basic_streambuf(3C++std), char_traits(3C++std)
Working Paper for Draft Proposed International Standard for Information
Systems--Programming Language C++.
STANDARDS CONFORMANCE
ANSI X3J16/ISO WG21 Joint C++ Committee
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