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                       Standard C++ Library
             Copyright 1998, Rogue Wave Software, Inc.


NAME
     basic_istringstream

      -     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

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