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


NAME
     num_get

      - A numeric formatting facet for input.



SYNOPSIS
     #include <locale>
     template <class charT, class InputIterator > class num_get;



DESCRIPTION
     The num_get facet allows for  formatted  input  of  numbers.
     basic_istream_and  all other input-oriented streams use this
     facet to implement formatted numeric input.



INTERFACE
     template <class charT, class InputIterator =
      istreambuf_iterator<charT> >
     class num_get : public locale::facet {
     public:
      typedef charT            char_type;
      typedef InputIterator    iter_type;
      explicit num_get(size_t refs = 0);
      iter_type get(iter_type, iter_type, ios_base&,
                    ios_base::iostate&, bool&)          const;
      iter_type get(iter_type, iter_type, ios_base& ,
                    ios_base::iostate&, long&)          const;
      iter_type get(iter_type, iter_type, ios_base&,
                    ios_base::iostate&, unsigned short&) const;
      iter_type get(iter_type, iter_type, ios_base&,
                    ios_base::iostate&, unsigned int&)  const;
      iter_type get(iter_type, iter_type, ios_base&,
                    ios_base::iostate&, unsigned long&) const;
      iter_type get(iter_type, iter_type, ios_base&,
                    ios_base::iostate&, float&)         const;
      iter_type get(iter_type, iter_type, ios_base&,
                    ios_base::iostate&, double&)        const;
      iter_type get(iter_type, iter_type, ios_base&,
                    ios_base::iostate&, long double&)   const;
      static locale::id id;

     protected:
       ~num_get();  // virtual
      virtual iter_type do_get(iter_type, iter_type, ios_base&,
                               ios_base::iostate&, bool&) const;
      virtual iter_type do_get(iter_type, iter_type, ios_base&,
                               ios_base::iostate&, long&) const;
      virtual iter_type do_get(iter_type, iter_type, ios_base&,
                               ios_base::iostate&,
                               unsigned short&) const;
      virtual iter_type do_get(iter_type, iter_type, ios_base&,
                               ios_base::iostate&,
                               unsigned int&) const;
      virtual iter_type do_get(iter_type, iter_type, ios_base&,
                               ios_base::iostate&,
                               unsigned long&) const;
      virtual iter_type do_get(iter_type, iter_type, ios_base&,
                               ios_base::iostate&, float&)
                               const;
      virtual iter_type do_get(iter_type, iter_type, ios_base&,
                               ios_base::iostate&, double&)
                               const;
      virtual iter_type do_get(iter_type, iter_type, ios_base&,
                               ios_base::iostate&,
                               long double&) const;
     };



TYPES
     char_type


        Type of character the facet is instantiated on.



     iter_type


        Type of iterator used to scan the character buffer.



CONSTRUCTORS
     explicit num_get(size_t refs = 0)


        Construct a num_get facet. If the  refs  argument  is  0,
        then  destruction  of  the  object  is  delegated  to the
        locale, or locales, containing it. This allows  the  user
        to  ignore lifetime management issues. On the other hand,
        if refs is 1, then the object must be explicitly deleted;
        the  locale  does not do so. In this case, the object can
        be maintained across the lifetime of multiple locales.



DESTRUCTORS
     ~num_get();  // virtual and protected


        Destroys the facet.



FACET ID
     static locale::id id;


        Unique identifier for this type of facet.



PUBLIC MEMBER FUNCTIONS
     The public members of the num_get facet include an interface
     to   protected   members.  Each  public  member  xxx  has  a
     corresponding virtual protected member do_xxx. All  work  is
     delegated to these protected members. For instance, the long
     version of the public get function  simply  calls  its  pro-
     tected cousin do_get.


     iter_type
     get(iter_type in, iter_type end, ios_base& io,
        ios_base::iostate& err, bool& v)          const;
     iter_type
     get(iter_type in, iter_type end, ios_base& io,
        ios_base::iostate& err, long& v)          const;
     iter_type
     get(iter_type in, iter_type end, ios_base& io,
        ios_base::iostate& err, unsigned short& v) const;
     iter_type
     get(iter_type in, iter_type end, ios_base& io,
        ios_base::iostate& err, unsigned int& v)  const;
     iter_type
     get(iter_type in, iter_type end, ios_base& io,
        ios_base::iostate& err, unsigned long& v) const;
     iter_type
     get(iter_type in, iter_type end, ios_base& io,
        ios_base::iostate& err, float& v) const;
     iter_type
     get(iter_type in, iter_type end, ios_base& io,
        ios_base::iostate& err, double& v) const;
     iter_type
     get(iter_type in, iter_type end, ios_base& io,
        ios_base::iostate& err, long double& v) const;


        Each of the eight overloads of the  get  function  simply
        call the corresponding do_get function.



PROTECTED MEMBER FUNCTIONS
     virtual iter_type
     do_get(iter_type in, iter_type end, ios_base& io,
           ios_base::iostate& err, bool& v) const;
     virtual iter_type
     do_get(iter_type in, iter_type end, ios_base& io,
           ios_base::iostate& err, long& v) const;
     virtual iter_type
     do_get(iter_type in, iter_type end, ios_base& io,
           ios_base::iostate& err,
           unsigned short& v) const;
     virtual iter_type
     do_get(iter_type in, iter_type end, ios_base& io,
           ios_base::iostate& err,
           unsigned int& v) const;
     virtual iter_type
     do_get(iter_type in, iter_type end, ios_base& io,
           ios_base::iostate& err,
           unsigned long& v) const;
     virtual iter_type
     do_get(iter_type in, iter_type end, ios_base& io,
           ios_base::iostate& err, float& v) const;
     virtual iter_type
     do_get(iter_type in, iter_type end, ios_base& io,
           ios_base::iostate& err, double& v) const;
     virtual iter_type
     do_get(iter_type in, iter_type end, ios_base& io,
           ios_base::iostate& long double& v) const;


        The eight overloads of the  do_get  member  function  all
        take  a  sequence  of characters [int,end), and extract a
        numeric value. The numeric value is returned in v.    The
        io  argument is used to obtain formatting information and
        the err argument is used to set  error  conditions  in  a
        calling stream.



EXAMPLE
     //
     // numget.cpp
     //

     #include <sstream>

     int main ()
     {
      using namespace std;

     typedef istreambuf_iterator<char,char_traits<char> >
      iter_type;

      locale loc;
      ios_base::iostate state;
      bool bval = false;
      long lval = 0L;
      long double ldval = 0.0;
      iter_type end;

       // Get a num_get facet
      const num_get<char,iter_type>& tg =
     #ifndef _RWSTD_NO_TEMPLATE_ON_RETURN_TYPE
      use_facet<num_get<char,iter_type> >(loc);
     #else
      use_facet(loc,(num_get<char,iter_type>*)0);
     #endif

       {
         // Build an istringstream from the buffer and construct
         // beginning and ending iterators on it.
        istringstream ins("true");
        iter_type begin(ins);

         // Get a bool value
        tg.get(begin,end,ins,state,bval);
       }
      cout << bval << endl;
       {
         // Get a long value
        istringstream ins("2422235");
        iter_type begin(ins);
        tg.get(begin,end,ins,state,lval);
       }
      cout << lval << endl;
       {
         // Get a long double value
        istringstream ins("32324342.98908");
        iter_type begin(ins);
        tg.get(begin,end,ins,state,ldval);
       }
      cout << ldval << endl;
      return 0;
     }



SEE ALSO
     locale, facets, num_put, numpunct, ctype

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