Public Types
- typedef ctype< _CharT > __ctype_type
-
typedef basic_filebuf
< char_type, traits_type > __filebuf_type -
typedef basic_ios< _CharT,
_Traits > __ios_type -
typedef basic_istream
< char_type, traits_type > __istream_type -
typedef num_get< _CharT,
istreambuf_iterator< _CharT,
_Traits > > __num_get_type -
typedef basic_streambuf
< _CharT, _Traits > __streambuf_type - typedef _CharT char_type
- typedef traits_type::int_type int_type
- typedef traits_type::off_type off_type
- typedef traits_type::pos_type pos_type
- typedef _Traits traits_type
Public Member Functions
- basic_ifstream ()
- basic_ifstream (const char *__s, ios_base::openmode __mode=ios_base::in)
- basic_ifstream (const std::string &__s, ios_base::openmode __mode=ios_base::in)
- ~basic_ifstream ()
- void close ()
- streamsize gcount () const
- bool is_open ()
- bool is_open () const
- void open (const char *__s, ios_base::openmode __mode=ios_base::in)
- void open (const std::string &__s, ios_base::openmode __mode=ios_base::in)
- __filebuf_type * rdbuf () const
- __istream_type & operator>> (__istream_type &(*__pf)(__istream_type &))
- __istream_type & operator>> (__ios_type &(*__pf)(__ios_type &))
- __istream_type & operator>> (ios_base &(*__pf)(ios_base &))
All the operator>> functions (aka formatted input functions) have some common behavior. Each starts by constructing a temporary object of type std::basic_istream::sentry with the second argument (noskipws) set to false. This has several effects, concluding with the setting of a status flag; see the sentry documentation for more.
If the sentry status is good, the function tries to extract whatever data is appropriate for the type of the argument.
If an exception is thrown during extraction, ios_base::badbit will be turned on in the stream's error state without causing an ios_base::failure to be thrown. The original exception will then be rethrown.
- __istream_type & operator>> (bool &__n)
- __istream_type & operator>> (short &__n)
- __istream_type & operator>> (unsigned short &__n)
- __istream_type & operator>> (int &__n)
- __istream_type & operator>> (unsigned int &__n)
- __istream_type & operator>> (long &__n)
- __istream_type & operator>> (unsigned long &__n)
- __istream_type & operator>> (long long &__n)
- __istream_type & operator>> (unsigned long long &__n)
- __istream_type & operator>> (float &__f)
- __istream_type & operator>> (double &__f)
- __istream_type & operator>> (long double &__f)
- __istream_type & operator>> (void *&__p)
- __istream_type & operator>> (__streambuf_type *__sb)
All the unformatted input functions have some common behavior. Each starts by constructing a temporary object of type std::basic_istream::sentry with the second argument (noskipws) set to true. This has several effects, concluding with the setting of a status flag; see the sentry documentation for more.
If the sentry status is good, the function tries to extract whatever data is appropriate for the type of the argument.
The number of characters extracted is stored for later retrieval by gcount().
If an exception is thrown during extraction, ios_base::badbit will be turned on in the stream's error state without causing an ios_base::failure to be thrown. The original exception will then be rethrown.
- int_type get ()
- __istream_type & get (char_type &__c)
- __istream_type & get (char_type *__s, streamsize __n, char_type __delim)
- __istream_type & get (char_type *__s, streamsize __n)
- __istream_type & get (__streambuf_type &__sb, char_type __delim)
- __istream_type & get (__streambuf_type &__sb)
- __istream_type & getline (char_type *__s, streamsize __n, char_type __delim)
- __istream_type & getline (char_type *__s, streamsize __n)
- __istream_type & ignore ()
- __istream_type & ignore (streamsize __n)
- __istream_type & ignore (streamsize __n, int_type __delim)
- int_type peek ()
- __istream_type & read (char_type *__s, streamsize __n)
- streamsize readsome (char_type *__s, streamsize __n)
- __istream_type & putback (char_type __c)
- __istream_type & unget ()
- int sync ()
- pos_type tellg ()
- __istream_type & seekg (pos_type)
- __istream_type & seekg (off_type, ios_base::seekdir)
Protected Member Functions
- __istream_type & _M_extract (_ValueT &__v)
Protected Attributes
Friends
Detailed Description
Controlling input for files.
This class supports reading from named files, using the inherited functions from std::basic_istream. To control the associated sequence, an instance of std::basic_filebuf is used, which this page refers to as sb.
Constructor & Destructor Documentation
| std::basic_ifstream::basic_ifstream | ( | ) | [inline] |
| std::basic_ifstream::basic_ifstream | ( | const char * | __s, |
| ios_base::openmode | __mode = ios_base::in |
||
| ) | [inline, explicit] |
Create an input file stream.
- Parameters:
-
s Null terminated string specifying the filename. mode Open file in specified mode (see std::ios_base).
ios_base::in is automatically included in mode.
Tip: When using std::string to hold the filename, you must use .c_str() before passing it to this constructor.
Definition at line 460 of file fstream.
References open().
| std::basic_ifstream::basic_ifstream | ( | const std::string & | __s, |
| ios_base::openmode | __mode = ios_base::in |
||
| ) | [inline, explicit] |
Create an input file stream.
- Parameters:
-
s std::string specifying the filename. mode Open file in specified mode (see std::ios_base).
ios_base::in is automatically included in mode.
Definition at line 476 of file fstream.
References open().
| std::basic_ifstream::~basic_ifstream | ( | ) | [inline] |
Member Function Documentation
| void std::basic_ifstream::close | ( | ) | [inline] |
Close the file.
Calls std::basic_filebuf::close(). If that function fails, failbit is set in the stream's error state.
Definition at line 569 of file fstream.
References std::basic_filebuf::close(), and std::ios_base::failbit.
| streamsize std::basic_istream::gcount | ( | ) | const [inline, inherited] |
| int_type std::basic_istream::get | ( | void | ) | [inherited] |
Simple extraction.
- Returns:
- A character, or eof().
Tries to extract a character. If none are available, sets failbit and returns traits::eof().
| __istream_type& std::basic_istream::get | ( | char_type & | __c | ) | [inherited] |
Simple extraction.
- Parameters:
-
c The character in which to store data.
- Returns:
- *this
Tries to extract a character and store it in c. If none are available, sets failbit and returns traits::eof().
- Note:
- This function is not overloaded on signed char and unsigned char.
| __istream_type& std::basic_istream::get | ( | char_type * | __s, |
| streamsize | __n, | ||
| char_type | __delim | ||
| ) | [inherited] |
Simple multiple-character extraction.
- Parameters:
-
s Pointer to an array. n Maximum number of characters to store in s. delim A "stop" character.
- Returns:
- *this
Characters are extracted and stored into s until one of the following happens:
n-1characters are stored- the input sequence reaches EOF
- the next character equals delim, in which case the character is not extracted
If no characters are stored, failbit is set in the stream's error state.
In any case, a null character is stored into the next location in the array.
- Note:
- This function is not overloaded on signed char and unsigned char.
| __istream_type& std::basic_istream::get | ( | char_type * | __s, |
| streamsize | __n | ||
| ) | [inline, inherited] |
| __istream_type& std::basic_istream::get | ( | __streambuf_type & | __sb, |
| char_type | __delim | ||
| ) | [inherited] |
Extraction into another streambuf.
- Parameters:
-
sb A streambuf in which to store data. delim A "stop" character.
- Returns:
- *this
Characters are extracted and inserted into sb until one of the following happens:
- the input sequence reaches EOF
- insertion into the output buffer fails (in this case, the character that would have been inserted is not extracted)
- the next character equals delim (in this case, the character is not extracted)
- an exception occurs (and in this case is caught)
If no characters are stored, failbit is set in the stream's error state.
| __istream_type& std::basic_istream::get | ( | __streambuf_type & | __sb | ) | [inline, inherited] |
| __istream_type& std::basic_istream::getline | ( | char_type * | __s, |
| streamsize | __n, | ||
| char_type | __delim | ||
| ) | [inherited] |
String extraction.
- Parameters:
-
s A character array in which to store the data. n Maximum number of characters to extract. delim A "stop" character.
- Returns:
- *this
Extracts and stores characters into s until one of the following happens. Note that these criteria are required to be tested in the order listed here, to allow an input line to exactly fill the s array without setting failbit.
- the input sequence reaches end-of-file, in which case eofbit is set in the stream error state
- the next character equals
delim, in which case the character is extracted (and therefore counted ingcount()) but not stored n-1characters are stored, in which case failbit is set in the stream error state
If no characters are extracted, failbit is set. (An empty line of input should therefore not cause failbit to be set.)
In any case, a null character is stored in the next location in the array.
| __istream_type& std::basic_istream::getline | ( | char_type * | __s, |
| streamsize | __n | ||
| ) | [inline, inherited] |
| __istream_type& std::basic_istream::ignore | ( | void | ) | [inherited] |
Discarding characters.
- Parameters:
-
n Number of characters to discard. delim A "stop" character.
- Returns:
- *this
Extracts characters and throws them away until one of the following happens:
- if n
!=std::numeric_limits<int>::max(), n characters are extracted - the input sequence reaches end-of-file
- the next character equals delim (in this case, the character is extracted); note that this condition will never occur if delim equals
traits::eof().
NB: Provide three overloads, instead of the single function (with defaults) mandated by the Standard: this leads to a better performing implementation, while still conforming to the Standard.
| __istream_type& std::basic_istream::ignore | ( | streamsize | __n | ) | [inherited] |
Simple extraction.
- Returns:
- A character, or eof().
Tries to extract a character. If none are available, sets failbit and returns traits::eof().
| __istream_type& std::basic_istream::ignore | ( | streamsize | __n, |
| int_type | __delim | ||
| ) | [inherited] |
Simple extraction.
- Returns:
- A character, or eof().
Tries to extract a character. If none are available, sets failbit and returns traits::eof().
| bool std::basic_ifstream::is_open | ( | ) | [inline] |
Wrapper to test for an open file.
Definition at line 510 of file fstream.
References std::basic_filebuf::is_open().
| void std::basic_ifstream::open | ( | const char * | __s, |
| ios_base::openmode | __mode = ios_base::in |
||
| ) | [inline] |
Opens an external file.
- Parameters:
-
s The name of the file. mode The open mode flags.
Calls std::basic_filebuf::open(s,mode|in). If that function fails, failbit is set in the stream's error state.
Tip: When using std::string to hold the filename, you must use .c_str() before passing it to this constructor.
Definition at line 531 of file fstream.
References std::basic_filebuf::open(), std::ios_base::in, and std::ios_base::failbit.
Referenced by basic_ifstream().
| void std::basic_ifstream::open | ( | const std::string & | __s, |
| ios_base::openmode | __mode = ios_base::in |
||
| ) | [inline] |
Opens an external file.
- Parameters:
-
s The name of the file. mode The open mode flags.
Calls std::basic_filebuf::open(s,mode|in). If that function fails, failbit is set in the stream's error state.
Definition at line 551 of file fstream.
References std::basic_filebuf::open(), std::ios_base::in, and std::ios_base::failbit.
| __istream_type& std::basic_istream::operator>> | ( | __istream_type &(*)(__istream_type &) | __pf | ) | [inline, inherited] |
| __istream_type& std::basic_istream::operator>> | ( | __ios_type &(*)(__ios_type &) | __pf | ) | [inline, inherited] |
| __istream_type& std::basic_istream::operator>> | ( | ios_base &(*)(ios_base &) | __pf | ) | [inline, inherited] |
| __istream_type& std::basic_istream::operator>> | ( | bool & | __n | ) | [inline, inherited] |
| __istream_type& std::basic_istream::operator>> | ( | short & | __n | ) | [inherited] |
Basic arithmetic extractors.
- Parameters:
-
A variable of builtin type.
- Returns:
*thisif successful
These functions use the stream's current locale (specifically, the num_get facet) to parse the input data.
| __istream_type& std::basic_istream::operator>> | ( | unsigned short & | __n | ) | [inline, inherited] |
| __istream_type& std::basic_istream::operator>> | ( | int & | __n | ) | [inherited] |
Basic arithmetic extractors.
- Parameters:
-
A variable of builtin type.
- Returns:
*thisif successful
These functions use the stream's current locale (specifically, the num_get facet) to parse the input data.
| __istream_type& std::basic_istream::operator>> | ( | unsigned int & | __n | ) | [inline, inherited] |
| __istream_type& std::basic_istream::operator>> | ( | long & | __n | ) | [inline, inherited] |
| __istream_type& std::basic_istream::operator>> | ( | unsigned long & | __n | ) | [inline, inherited] |
| __istream_type& std::basic_istream::operator>> | ( | long long & | __n | ) | [inline, inherited] |
| __istream_type& std::basic_istream::operator>> | ( | unsigned long long & | __n | ) | [inline, inherited] |
| __istream_type& std::basic_istream::operator>> | ( | float & | __f | ) | [inline, inherited] |
| __istream_type& std::basic_istream::operator>> | ( | double & | __f | ) | [inline, inherited] |
| __istream_type& std::basic_istream::operator>> | ( | long double & | __f | ) | [inline, inherited] |
| __istream_type& std::basic_istream::operator>> | ( | void *& | __p | ) | [inline, inherited] |
| __istream_type& std::basic_istream::operator>> | ( | __streambuf_type * | __sb | ) | [inherited] |
Extracting into another streambuf.
- Parameters:
-
sb A pointer to a streambuf
This function behaves like one of the basic arithmetic extractors, in that it also constructs a sentry object and has the same error handling behavior.
If sb is NULL, the stream will set failbit in its error state.
Characters are extracted from this stream and inserted into the sb streambuf until one of the following occurs:
- the input stream reaches end-of-file,
- insertion into the output buffer fails (in this case, the character that would have been inserted is not extracted), or
- an exception occurs (and in this case is caught)
If the function inserts no characters, failbit is set.
| int_type std::basic_istream::peek | ( | void | ) | [inherited] |
Looking ahead in the stream.
- Returns:
- The next character, or eof().
If, after constructing the sentry object, good() is false, returns traits::eof(). Otherwise reads but does not extract the next input character.
| __istream_type& std::basic_istream::putback | ( | char_type | __c | ) | [inherited] |
Unextracting a single character.
- Parameters:
-
c The character to push back into the input stream.
- Returns:
- *this
If rdbuf() is not null, calls rdbuf()->sputbackc(c).
If rdbuf() is null or if sputbackc() fails, sets badbit in the error state.
- Note:
- This function first clears eofbit. Since no characters are extracted, the next call to
gcount()will return 0, as required by DR 60.
| __filebuf_type* std::basic_ifstream::rdbuf | ( | ) | const [inline] |
Accessing the underlying buffer.
- Returns:
- The current basic_filebuf buffer.
This hides both signatures of std::basic_ios::rdbuf().
| __istream_type& std::basic_istream::read | ( | char_type * | __s, |
| streamsize | __n | ||
| ) | [inherited] |
Extraction without delimiters.
- Parameters:
-
s A character array. n Maximum number of characters to store.
- Returns:
- *this
If the stream state is good(), extracts characters and stores them into s until one of the following happens:
- n characters are stored
- the input sequence reaches end-of-file, in which case the error state is set to
failbit|eofbit.
- Note:
- This function is not overloaded on signed char and unsigned char.
| streamsize std::basic_istream::readsome | ( | char_type * | __s, |
| streamsize | __n | ||
| ) | [inherited] |
Extraction until the buffer is exhausted, but no more.
- Parameters:
-
s A character array. n Maximum number of characters to store.
- Returns:
- The number of characters extracted.
Extracts characters and stores them into s depending on the number of characters remaining in the streambuf's buffer, rdbuf()->in_avail(), called A here:
- if
A==-1, sets eofbit and extracts no characters - if
A==0, extracts no characters - if
A>0, extractsmin(A,n)
The goal is to empty the current buffer, and to not request any more from the external input sequence controlled by the streambuf.
| __istream_type& std::basic_istream::seekg | ( | pos_type | ) | [inherited] |
Changing the current read position.
- Parameters:
-
pos A file position object.
- Returns:
- *this
If fail() is not true, calls rdbuf()->pubseekpos(pos). If that function fails, sets failbit.
- Note:
- This function first clears eofbit. It does not count the number of characters extracted, if any, and therefore does not affect the next call to
gcount().
| __istream_type& std::basic_istream::seekg | ( | off_type | , |
| ios_base::seekdir | |||
| ) | [inherited] |
Changing the current read position.
- Parameters:
-
off A file offset object. dir The direction in which to seek.
- Returns:
- *this
If fail() is not true, calls rdbuf()->pubseekoff(off,dir). If that function fails, sets failbit.
- Note:
- This function first clears eofbit. It does not count the number of characters extracted, if any, and therefore does not affect the next call to
gcount().
| int std::basic_istream::sync | ( | void | ) | [inherited] |
Synchronizing the stream buffer.
- Returns:
- 0 on success, -1 on failure
If rdbuf() is a null pointer, returns -1.
Otherwise, calls rdbuf()->pubsync(), and if that returns -1, sets badbit and returns -1.
Otherwise, returns 0.
- Note:
- This function does not count the number of characters extracted, if any, and therefore does not affect the next call to
gcount().
| pos_type std::basic_istream::tellg | ( | void | ) | [inherited] |
Getting the current read position.
- Returns:
- A file position object.
If fail() is not false, returns pos_type(-1) to indicate failure. Otherwise returns rdbuf()->pubseekoff(0,cur,in).
- Note:
- This function does not count the number of characters extracted, if any, and therefore does not affect the next call to
gcount(). At variance with putback, unget and seekg, eofbit is not cleared first.
| __istream_type& std::basic_istream::unget | ( | void | ) | [inherited] |
Unextracting the previous character.
- Returns:
- *this
If rdbuf() is not null, calls rdbuf()->sungetc(c).
If rdbuf() is null or if sungetc() fails, sets badbit in the error state.
- Note:
- This function first clears eofbit. Since no characters are extracted, the next call to
gcount()will return 0, as required by DR 60.
Member Data Documentation
streamsize std::basic_istream::_M_gcount [protected, inherited] |
The documentation for this class was generated from the following file:
