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VMS Help CXXLSTD, IOStreams, istringstream *Conan The Librarian |
Standard C++ Library
Copyright 1996, Rogue Wave Software, Inc.
NAME
basic_istringstream
SYNOPSIS
#include <sstream>
template<class charT, class traits = char_traits<charT>,
class Allocator = allocator<void> >
class basic_istringstream
: public basic_istream<charT, traits>
DESCRIPTION
The template class basic_istringstream<charT,traits,Allocator>
provides functionality to read 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 parameter 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 parameter 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,
initializing the base class basic_istream with the
associated string buffer. The string buffer is ini-
tialized 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,
initializing the base class basic_istream with the
associated string buffer. The string buffer is ini-
tialized by calling the basic_stringbuf constructor
basic_stringbuf<charT,traits,Allocator>(str,which).
DESTRUCTOR
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 contains 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, initialize the input
sequence to point at the first character of the buffer. If
the opening mode is out, initialize the output sequence to
point at the first character of the buffer. If the opening
mode is out | app, initialize the output sequence to point at
the last character of the buffer.
EXAMPLES
//
// 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, ios_base, basic_ios,
basic_stringbuf, basic_string,
basic_ostringstream, basic_stringstream
Working Paper for Draft Proposed International Standard for
Information Systems--Programming Language C++, Section 27.7.2
STANDARDS CONFORMANC
ANSI X3J16/ISO WG21 Joint C++ Committee
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