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Difference between revisions of "cpp/io/basic filebuf"

From cppreference.com
< cpp‎ | io
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{{tt|std::basic_filebuf}} is a {{cpp|std::basic_streambuf}} whose associated character sequence is a file. Both the input sequence and the output sequence are associated with the same file, and a joint file position is maintained for both operations.
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{{tt|std::basic_filebuf}} is a {{c|std::basic_streambuf}} whose associated character sequence is a file. Both the input sequence and the output sequence are associated with the same file, and a joint file position is maintained for both operations.
  
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The functions underflow() and overflow()/sync() perform the actual I/O between the file and the get and put areas of the buffer. When {{tt|CharT}} is not {{cpp|char}}, most implementations store multibyte characters in the file and a {{cpp|std::codecvt}} facet is used to perform wide/multibyte character conversion.
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The functions underflow() and overflow()/sync() perform the actual I/O between the file and the get and put areas of the buffer. When {{tt|CharT}} is not {{c|char}}, most implementations store multibyte characters in the file and a {{c|std::codecvt}} facet is used to perform wide/multibyte character conversion.
  
 
Two specializations for common character types are also defined:
 
Two specializations for common character types are also defined:
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{{tdcl list header | streambuf}}
 
{{tdcl list header | streambuf}}
 
{{tdcl list hitem | Type | Definition}}
 
{{tdcl list hitem | Type | Definition}}
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{{tdcl list item | {{tt|filebuf}} | {{cpp|basic_filebuf<char>}}}}
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{{tdcl list item | {{tt|filebuf}} | {{c|basic_filebuf<char>}}}}
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{{tdcl list item | {{tt|wfilebuf}} | {{cpp|basic_filebuf<wchar_t>}}}}
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{{tdcl list item | {{tt|wfilebuf}} | {{c|basic_filebuf<wchar_t>}}}}
 
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{{tdcl list template | cpp/io/tdcl list traits_type}}
 
{{tdcl list template | cpp/io/tdcl list traits_type}}
 
{{tdcl list template | cpp/io/tdcl list int_type}}
 
{{tdcl list template | cpp/io/tdcl list int_type}}
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{{tdcl list item | {{tt|pos_type}} | {{cpp|Traits::pos_type}} which is required to be {{cpp|std::fpos<Traits::state_type>}}}}
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{{tdcl list item | {{tt|pos_type}} | {{c|Traits::pos_type}} which is required to be {{c|std::fpos<Traits::state_type>}}}}
 
{{tdcl list template | cpp/io/tdcl list off_type}}
 
{{tdcl list template | cpp/io/tdcl list off_type}}
 
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Revision as of 18:59, 19 April 2012

Template:cpp/io/basic filebuf/sidebar

Defined in header <fstream>
template<

    class charT,
    class Traits = std::char_traits<CharT>,
    class Allocator = std::allocator<CharT>

> class basic_filebuf : public std::basic_streambuf<CharT, Traits>

std::basic_filebuf is a std::basic_streambuf whose associated character sequence is a file. Both the input sequence and the output sequence are associated with the same file, and a joint file position is maintained for both operations.

The functions underflow() and overflow()/sync() perform the actual I/O between the file and the get and put areas of the buffer. When CharT is not char, most implementations store multibyte characters in the file and a std::codecvt facet is used to perform wide/multibyte character conversion.

Two specializations for common character types are also defined:

Template:tdcl list begin Template:tdcl list header Template:tdcl list hitem Template:tdcl list item Template:tdcl list item Template:tdcl list end

Contents

Member types

Template:tdcl list begin Template:tdcl list hitem Template:tdcl list template Template:tdcl list template Template:tdcl list template Template:tdcl list item Template:tdcl list template Template:tdcl list end

Member functions

Template:cpp/io/basic filebuf/dcl list basic filebufTemplate:cpp/io/basic filebuf/dcl list operator=Template:cpp/io/basic filebuf/dcl list swapTemplate:cpp/io/basic filebuf/dcl list ~basic filebufTemplate:cpp/io/basic filebuf/dcl list is openTemplate:cpp/io/basic filebuf/dcl list openTemplate:cpp/io/basic filebuf/dcl list closeTemplate:cpp/io/basic filebuf/dcl list showmanycTemplate:cpp/io/basic filebuf/dcl list underflowTemplate:cpp/io/basic filebuf/dcl list uflowTemplate:cpp/io/basic filebuf/dcl list pbackfailTemplate:cpp/io/basic filebuf/dcl list overflowTemplate:cpp/io/basic filebuf/dcl list setbufTemplate:cpp/io/basic filebuf/dcl list seekoffTemplate:cpp/io/basic filebuf/dcl list seekposTemplate:cpp/io/basic filebuf/dcl list syncTemplate:cpp/io/basic filebuf/dcl list imbue

Public member functions

Protected member functions

Non-member functions

Template:cpp/io/basic filebuf/dcl list swap2

Inherited from std::basic_streambuf

Member types

Member type Definition
char_type CharT[edit]
traits_type Traits; the program is ill-formed if Traits::char_type is not CharT.[edit]
int_type Traits::int_type[edit]
pos_type Traits::pos_type[edit]
off_type Traits::off_type[edit]

Member functions

[virtual]
 destructs the basic_streambuf object
(virtual public member function of std::basic_streambuf<CharT,Traits>) [edit]
Locales
invokes imbue()
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
obtains a copy of the associated locale
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
Positioning
invokes setbuf()
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
invokes seekoff()
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
invokes seekpos()
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
invokes sync()
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
Get area
obtains the number of characters immediately available in the get area
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
advances the input sequence, then reads one character without advancing again
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
(removed in C++17)
 reads one character from the input sequence and advances the sequence
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
reads one character from the input sequence without advancing the sequence
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
invokes xsgetn()
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
Put area
writes one character to the put area and advances the next pointer
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
invokes xsputn()
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
Putback
puts one character back in the input sequence
(public member function of std::basic_streambuf<CharT,Traits>) [edit]
moves the next pointer in the input sequence back by one
(public member function of std::basic_streambuf<CharT,Traits>) [edit]

Protected member functions

 constructs a basic_streambuf object
(protected member function) [edit]
(C++11)
 replaces a basic_streambuf object
(protected member function) [edit]
(C++11)
 swaps two basic_streambuf objects
(protected member function) [edit]
Locales
[virtual]
 changes the associated locale
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
Positioning
[virtual]
 replaces the buffer with user-defined array, if permitted
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
[virtual]
 repositions the next pointer in the input sequence, output sequence, or both, using relative addressing
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
[virtual]
 repositions the next pointer in the input sequence, output sequence, or both using absolute addressing
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
[virtual]
 synchronizes the buffers with the associated character sequence
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
Get area
[virtual]
 obtains the number of characters available for input in the associated input sequence, if known
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
[virtual]
 reads characters from the associated input sequence to the get area
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
[virtual]
 reads characters from the associated input sequence to the get area and advances the next pointer
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
[virtual]
 reads multiple characters from the input sequence
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
returns a pointer to the beginning, current character and the end of the get area
(protected member function) [edit]
advances the next pointer in the input sequence
(protected member function) [edit]
repositions the beginning, next, and end pointers of the input sequence
(protected member function) [edit]
Put area
[virtual]
 writes multiple characters to the output sequence
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
[virtual]
 writes characters to the associated output sequence from the put area
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
returns a pointer to the beginning, current character and the end of the put area
(protected member function) [edit]
advances the next pointer of the output sequence
(protected member function) [edit]
repositions the beginning, next, and end pointers of the output sequence
(protected member function) [edit]
Putback
[virtual]
 puts a character back into the input sequence, possibly modifying the input sequence
(virtual protected member function of std::basic_streambuf<CharT,Traits>) [edit]
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