namespace std {
template <class charT>
class numpunct : public locale::facet {
public:
typedef charT char_type;
typedef basic_string<charT> string_type;
explicit numpunct(size_t refs = 0);
char_type decimal_point() const;
char_type thousands_sep() const;
string grouping() const;
string_type truename() const;
string_type falsename() const;
static locale::id id;
protected:
~numpunct(); // virtual
virtual char_type do_decimal_point() const;
virtual char_type do_thousands_sep() const;
virtual string do_grouping() const;
virtual string_type do_truename() const; // for bool
virtual string_type do_falsename() const; // for bool
};
}
numpunct<> specifies numeric punctuation. The specializations required in Table [tab:localization.category.facets] ([locale.category]), namely numpunct<wchar_t> and numpunct<char>, provide classic "C" numeric formats, i.e., they contain information equivalent to that contained in the "C" locale or their wide character counterparts as if obtained by a call to widen.
The syntax for number formats is as follows, where digit represents the radix set specified by the fmtflags argument value, and thousands-sep and decimal-point are the results of corresponding numpunct<charT> members. Integer values have the format:
integer ::= [sign] units sign ::= plusminus plusminus ::= '+' | '-' units ::= digits [thousands-sep units] digits ::= digit [digits]
and floating-point values have:
floatval ::= [sign] units [decimal-point [digits]] [e [sign] digits] |
[sign] decimal-point digits [e [sign] digits]
e ::= 'e' | 'E'
where the number of digits between thousands-seps is as specified by do_grouping(). For parsing, if the digits portion contains no thousands-separators, no grouping constraint is applied.
char_type decimal_point() const;
Returns: do_decimal_point()
char_type thousands_sep() const;
Returns: do_thousands_sep()
Returns: do_grouping()
string_type truename() const;
string_type falsename() const;
Returns: do_truename() or do_falsename(), respectively.
char_type do_decimal_point() const;
Returns: A character for use as the decimal radix separator. The required specializations return '.' or L'.'.
char_type do_thousands_sep() const;
Returns: A character for use as the digit group separator. The required specializations return ',' or L','.
Returns: A basic_string<char> vec used as a vector of integer values, in which each element vec[i] represents the number of digits248 in the group at position i, starting with position 0 as the rightmost group. If vec.size() <= i, the number is the same as group (i-1); if (i<0 || vec[i]<=0 || vec[i]==CHAR_MAX), the size of the digit group is unlimited.
The required specializations return the empty string, indicating no grouping.
string_type do_truename() const;
string_type do_falsename() const;
Returns: A string representing the name of the boolean value true or false, respectively.
In the base class implementation these names are "true" and "false", or L"true" and L"false".
Thus, the string "\003" specifies groups of 3 digits each, and "3" probably indicates groups of 51 (!) digits each, because 51 is the ASCII value of "3".
namespace std {
template <class charT>
class numpunct_byname : public numpunct<charT> {
// this class is specialized for char and wchar_t.
public:
typedef charT char_type;
typedef basic_string<charT> string_type;
explicit numpunct_byname(const char*, size_t refs = 0);
explicit numpunct_byname(const string&, size_t refs = 0);
protected:
~numpunct_byname();
};
}