ostream/istream

출처:http://www.cplusplus.com/reference/iostream/istream/

Output Stream

ios_base		ios		ostream		iostream
						ofstream
						ostringstream

ostream objects are stream objects used to write and format output as sequences of characters. Specific members are provided to perform these output operations, which can be divided in two main groups:

• Formatted output
  These member functions interpret and format the data to be written as sequences of characters. These type of operation is performed using member and global functions that overload the insertion operator (operator<<).
• Unformatted output
  Most of the other member functions of the ostream class are used to perform unformatted output operations, i.e. output operations that write the data as it is, with no formatting adaptations. These member functions can write a determined number of characters to the output character sequence (put, write) and manipulate the put pointer (seekp, tellp).
  

Additionaly, a member function exists to synchronize the stream with the associated external destination of characters: sync.

The standard objects cout, cerr and clog are instantiations of this class.

The class inherits all the internal fields from its parent classes ios_base and ios:

Formatting information

• format flags: a set of internal indicators describing how certain input/output operations shall be interpreted or generated. The state of these indicators can be obtained or modified by calling the members flags, setf and unsetf, or by using manipulators.
• field width: describes the width of the next element to be output. This value can be obtained/modified by calling the member function width or parameterized manipulator setw.
• display precision: describes the decimal precision to be used to output floating-point values. This value can be obtained/modified by calling member precision or parameterized manipulator setprecision.
• fill character: character used to pad a field up to the field width. It can be obtained or modified by calling member function fill or parameterized manipulator setfill.
• locale object: describes the localization properties to be considered when formatting i/o operations. The locale object used can be obtained calling member getloc and modified using member imbue.

State information

• error state: internal indicator reflecting the integrity and current error state of the stream. The current object may be obtained by calling rdstate and can be modified by calling clear and setstate. Individual values may be obtained by calling good, eof, fail and bad.
• exception mask: internal exception status indicator. Its value can be retrieved/modified by calling member exceptions.

Other

• event function stack: stack of pointers to callback functions that are called when certain events occur. Additional callback functions may be registered to be called when an event occurs, using member function register_callback.
• internal extensible arrays: two internal arrays to store long objects and void pointers. These arrays can be extended by calling member function xalloc, and references to these objects can be retrieved with iword or pword.
• pointer to tied stream: pointer to the stream object which is tied to this stream object. It can be obtained/modified by calling member function tie.
• pointer to stream buffer: pointer to the associated streambuf object. It can be obtained/modified by calling member function rdbuf.

Public members

(constructor)

Construct object (constructor member)

(destructor)

Destruct object (destructor member)

Formatted output:

operator<<

Insert data with format (public member function)

Unformatted output:

put	Put character (public member function)

write

Write block of data (public member function)

Positioning:

tellp

Get position of put pointer (public member function)

seekp

Set position of put pointer (public member function)

Synchronization:

flush

Flush output stream buffer (public member function)

Prefix/Suffix:

sentry

Perform exception safe prefix/suffix operations (public member classes)

Member functions inherited from ios

good	Check if the state of the stream is good for i/o operations. (public member function)

eof	Check if eofbit is set (public member function)

fail	Check if either failbit or badbit is set (public member function)

bad	Check if badbit is set (public member function)

operator!

Evaluate stream object (public member function)

operator void*

Convert to pointer (public member function)

rdstate

Get error state flags (public member function)

setstate

Set error state flag (public member function)

clear

Set error state flags (public member function)

copyfmt

Copy formatting information (public member functions)

fill	Get/set the fill character (public member function)

exceptions

Get/set exception mask (public member function)

imbue

Imbue locale (public member function)

tie	Get/set the tied stream (public member function)

rdbuf

Get/set the associated stream buffer (public member function)

narrow

Narrow character (public member function)

widen

Widen character (public member function)

Member functions inherited from ios_base

flags

Get/set format flags (public member function)

setf	Set specific format flags (public member function)

unsetf

Clear specific format flags (public member function)

precision

Get/Set floating-point decimal precision (public member function)

width

Get/set field width (public member function)

imbue

Imbue locale (public member function)

getloc

Get current locale (public member function)

xalloc

Return a new index for the internal extensible array [static] (public static member function)

iword

Get reference to integer element of the internal extensible array (public member function)

pword

Get reference to pointer of the internal extensible array (public member function)

register_callback

Register event callback function (public member function)

sync_with_stdio

Activate/deactivate synchronization of iostream and cstdio streams [static] (public static member function)

---

istream

class

<istream>

Input stream

ios_base		ios		istream		iostream
						ifstream
						istringstream

istream objects are stream objects used to read and interpret input from sequences of characters. Specific members are provided to perform these input operations, which can be divided in two main groups:

• Formatted input
  These functions extract data from a sequence of characters that may be interpreted and formatted to a value of a certain type. These type of operation is performed using member and global functions that overload the extraction operator ().
• Unformatted input
  Most of the other member functions of the istream class are used to perform unformatted input, i.e. no interpretation is made on the characters got form the input. These member functions can get a determined number of characters from the input character sequence (get, getline, peek, read, readsome), manipulate the get pointer i(ignore, seekg, tellg, unget) or get information of the last unformatted input operation (gcount).
  

Additionaly, a member function exists to synchronize the stream with the associated external source of characters: sync.

The standard object cin is an instantiation of this class.

The class inherits all the internal fields from its parent classes ios_base and ios:

Formatting information

• format flags: a set of internal indicators describing how certain input/output operations shall be interpreted or generated. The state of these indicators can be obtained or modified by calling the members flags, setf and unsetf, or by using manipulators.
• field width: describes the width of the next element to be output. This value can be obtained/modified by calling the member function width or parameterized manipulator setw.
• display precision: describes the decimal precision to be used to output floating-point values. This value can be obtained/modified by calling member precision or parameterized manipulator setprecision.
• fill character: character used to pad a field up to the field width. It can be obtained or modified by calling member function fill or parameterized manipulator setfill.
• locale object: describes the localization properties to be considered when formatting i/o operations. The locale object used can be obtained calling member getloc and modified using member imbue.

State information

• error state: internal indicator reflecting the integrity and current error state of the stream. The current object may be obtained by calling rdstate and can be modified by calling clear and setstate. Individual values may be obtained by calling good, eof, fail and bad.
• exception mask: internal exception status indicator. Its value can be retrieved/modified by calling member exceptions.

Other

• event function stack: stack of pointers to callback functions that are called when certain events occur. Additional callback functions may be registered to be called when an event occurs, using member function register_callback.
• internal extensible arrays: two internal arrays to store long objects and void pointers. These arrays can be extended by calling member function xalloc, and references to these objects can be retrieved with iword or pword.
• pointer to tied stream: pointer to the stream object which is tied to this stream object. It can be obtained/modified by calling member function tie.
• pointer to stream buffer: pointer to the associated streambuf object. It can be obtained/modified by calling member function rdbuf.

Public members

(constructor)

Construct object (constructor member)

(destructor)

Destruct object (destructor member)

Formatted input:

operator>>

Extract formatted data (public member function)

Unformatted input:

gcount

Get number of characters extracted by last unformatted input operation (public member function)

get	Get unformatted data from stream (public member function)

getline

Get line from stream (public member function)

ignore

Extract and discard characters (public member functions)

peek	Peek next character (public member function)

read	Read block of data (public member function)

readsome

Read block of data available in the buffer (public member function)

putback

Put character back (public member function)

unget

Decrement get pointer (public member function)

Positioning:

tellg

Get position of the get pointer. (public member function)

seekg

Set position of the get pointer (public member function)

Synchronization:

sync	Synchronize input buffer with source of characters (public member function)

Prefix/Suffix:

sentry

Perform exception safe prefix/suffix operations (public member class)

Member functions inherited from ios

good	Check if the state of the stream is good for i/o operations. (public member function)

eof	Check if eofbit is set (public member function)

fail	Check if either failbit or badbit is set (public member function)

bad	Check if badbit is set (public member function)

operator!

Evaluate stream object (public member function)

operator void*

Convert to pointer (public member function)

rdstate

Get error state flags (public member function)

setstate

Set error state flag (public member function)

clear

Set error state flags (public member function)

copyfmt

Copy formatting information (public member functions)

fill	Get/set the fill character (public member function)

exceptions

Get/set exception mask (public member function)

imbue

Imbue locale (public member function)

tie	Get/set the tied stream (public member function)

rdbuf

Get/set the associated stream buffer (public member function)

narrow

Narrow character (public member function)

widen

Widen character (public member function)

Member functions inherited from ios_base

flags

Get/set format flags (public member function)

setf	Set specific format flags (public member function)

unsetf

Clear specific format flags (public member function)

precision

Get/Set floating-point decimal precision (public member function)

width

Get/set field width (public member function)

imbue

Imbue locale (public member function)

getloc

Get current locale (public member function)

xalloc

Return a new index for the internal extensible array [static] (public static member function)

iword

Get reference to integer element of the internal extensible array (public member function)

pword

Get reference to pointer of the internal extensible array (public member function)

register_callback

Register event callback function (public member function)

sync_with_stdio

Activate/deactivate synchronization of iostream and cstdio streams [static] (public static member function)