num_get(3C++)
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 protected 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
Rogue Wave Software — Last change: 02 Apr 1998