Standard C++ Library
Copyright 1998, Rogue Wave Software, Inc.
NAME
basic_istringstream, istringstream, wistringstream
- Supports reading objects of class
basic_string<charT,traits,Allocator> from an array in
memory.
SYNOPSIS
#include <sstream>
template<class charT, class traits = char_traits<charT>,
class Allocator = allocator<charT> >
class basic_istringstream
: public basic_istream<charT, traits>
DESCRIPTION
The template class
basic_istringstream<charT,traits,Allocator> reads from an
array in memory. It supports reading objects of class
basic_string<charT,traits,Allocator>. It uses a
basic_stringbuf object to control the associated storage. It
inherits from basic_istream and therefore can use all the
formatted and unformatted input functions.
INTERFACE
template<class charT, class traits = char_traits<charT>,
class Allocator = allocator<void> >
class basic_istringstream
: public basic_istream<charT, traits> {
public:
typedef basic_stringbuf<charT, traits, Allocator> sb_type;
typedef basic_ios<charT, traits> ios_type;
typedef basic_string<charT, traits, Allocator>
string_type;
typedef traits traits_type;
typedef charT char_type;
typedef typename traits::int_type int_type;
typedef typename traits::pos_type pos_type;
typedef typename traits::off_type off_type;
explicit basic_istringstream(ios_base::openmode which =
ios_base::in);
explicit basic_istringstream(const string_type& str,
ios_base::openmode which =
ios_base::in);
virtual ~basic_istringstream();
basic_stringbuf<charT,traits,Allocator> *rdbuf() const;
string_type str() const;
void str(const string_type& str);
};
TYPES
char_type
The type char_type is a synonym for the template parame-
ter charT.
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.
istringstream
The type istringstream is an instantiation of class
basic_istringstream on type char:
typedef basic_istringstream<char> istringstream;
off_type
The type off_type is a synonym of type traits::off_type.
pos_type
The type pos_type is a synonym of type traits::pos_type.
sb_type
The type sb_type is an instantiation of class
basic_stringbuf on type charT.
string_type
The type string_type is an instantiation of class
basic_string on type charT.
traits_type
The type traits_type is a synonym for the template param-
eter traits.
wistringstream
The type wistringstream is an instantiation of class
basic_istringstream on type wchar_t:
typedef basic_istringstream<wchar_t> wistringstream;
CONSTRUCTORS
explicit basic_istringstream(ios_base::openmode which =
ios_base::in);
Constructs an object of class basic_istringstream, ini-
tializing the base class basic_istream with the associ-
ated string buffer. The string buffer is initialized by
calling the basic_stringbuf constructor
basic_stringbuf<charT,traits,Allocator>(which).
explicit basic_istringstream(const string_type& str,
ios_base::openmode which =
ios_base::in);
Constructs an object of class basic_istringstream, ini-
tializing the base class basic_istream with the associ-
ated string buffer. The string buffer is initialized by
calling the basic_stringbuf constructor
basic_stringbuf<charT,traits,Allocator>(str,which).
DESTRUCTORS
virtual ~basic_istringstream();
Destroys an object of class basic_istringstream.
MEMBER FUNCTIONS
basic_stringbuf<charT,traits,Allocator>*
rdbuf() const;
Returns a pointer to the basic_stringbuf associated with
the stream.
string_type
str() const;
Returns a string object of type string_type, which con-
tains a copy of the underlying buffer contents.
void
str(const string_type& str);
Clears the string buffer and copies the string object str
into it. If the opening mode is in, initializes the input
sequence to point to the first character of the buffer.
If the opening mode is out, initializes the output
sequence to point to the first character of the buffer.
If the opening mode is out | app, initializes the output
sequence to point to the last character of the buffer.
EXAMPLE
//
// stdlib/examples/manual/istringstream.cpp
//
#include<iostream>
#include<sstream>
#include<string>
#include<iomanip>
void main ( )
{
using namespace std;
long l= 20;
wchar_t *ntbs=L"Il avait l'air heureux";
wchar_t c;
wchar_t buf[50];
// create a read/write string-stream object on wide char
// and attach it to an wistringstream object
wistringstream in(ios_base::in | ios_base::out);
// tie the ostream object to the wistringstream object
wostream out(in.rdbuf());
// output ntbs in out
out << ntbs;
// output each word on a separate line
while ( in.get(c) )
{
if ( c == L' ' )
wcout << endl;
else
wcout << c;
}
wcout << endl << endl;
// move back the input sequence to the beginning
in.seekg(0);
// clear the state flags
in.clear();
// does the same thing as the previous code
// output each word on a separate line
while ( in >> buf )
wcout << buf << endl;
wcout << endl << endl;
// create a tiny string object
string test_string("Il dormait pour l'eternite");
// create a read/write string-stream object on char
// and attach it to an istringstream object
istringstream in_bis(ios_base:: in | ios_base::out |
ios_base::app );
// create an ostream object
ostream out_bis(in_bis.rdbuf());
// initialize the string buffer with test_string
in_bis.str(test_string);
out_bis << endl;
// output the base info before each integer
out_bis << showbase;
ostream::pos_type pos= out_bis.tellp();
// output l in hex with a field with of 20
out_bis << hex << setw(20) << l << endl;
// output l in oct with a field with of 20
out_bis << oct << setw(20) << l << endl;
// output l in dec with a field with of 20
out_bis << dec << setw(20) << l << endl;
// output the all buffer
cout << in_bis.rdbuf();
// seek the input sequence to pos
in_bis.seekg(pos);
int a,b,d;
// read the previous outputted integer
in_bis >> a >> b >> d;
// output 3 times 20
cout << a << endl << b << endl << d << endl;
}
SEE ALSO
char_traits(3C++), ios_base(3C++), basic_ios(3C++),
basic_stringbuf(3C++), basic_string(3C++),
basic_ostringstream(3C++), basic_stringstream(3C++)
Working Paper for Draft Proposed International Standard for
Information Systems--Programming Language C++, Section
27.7.2
STANDARDS CONFORMANCE
ANSI X3J16/ISO WG21 Joint C++ Committee