Library: Localization
locale::facet moneypunct_byname
Monetary punctuation facets
#include <locale>
namespace std {
class money_base;
template <class charT, bool International = false>
class moneypunct;
template <class charT, bool International = false>
class moneypunct_byname;
}
template<> class moneypunct<char, false>; template<> class moneypunct<char, true>; template<> class moneypunct<wchar_t, false>; template<> class moneypunct<wchar_t, true>; template<> class moneypunct_byname<char, false>; template<> class moneypunct_byname<char, true>; template<> class moneypunct_byname<wchar_t, false>; template<> class moneypunct_byname<wchar_t, true>;
The moneypunct facets include formatting specifications and punctuation character for monetary values. The moneypunct facet is used with the C locale, while the moneypunct_byname facet is used with named locales.
The facet is used by money_put for outputting formatted representations of monetary values and by money_get for reading these strings back in.
money_base defines a structure, pattern, that specifies the order of syntactic elements in a monetary value and enumeration values representing those elements. The pattern struct includes a simple array of characters, field. Each index in field is taken up by an enumeration value indicating the location of a syntactic element. The enumeration values are described below:
| Format Flag | Value | Meaning |
none |
0 |
No grouping separator. |
space |
1 |
Use space for grouping separator. |
symbol |
2 |
Currency symbol. |
sign |
3 |
Sign of monetary value. |
value |
4 |
The monetary value itself. |
The do_pos_format() and do_neg_format() member functions of moneypunct both return values of the pattern type. See the description of these functions for further elaboration.
namespace std {
class money_base {
public:
enum part { none, space, symbol, sign, value };
struct pattern { char field[4]; };
};
template <class charT, bool International = false>
class moneypunct : public locale::facet, public money_base
{
public:
typedef charT char_type;
typedef basic_string<charT> string_type;
explicit moneypunct(size_t = 0);
charT decimal_point() const;
charT thousands_sep() const;
string grouping() const;
string_type curr_symbol() const;
string_type positive_sign() const;
string_type negative_sign() const;
int frac_digits() const;
pattern pos_format() const;
pattern neg_format() const;
static locale::id id;
static const bool intl = International;
};
template <class charT, bool Intl = false>
class moneypunct_byname : public moneypunct<charT, Intl>
{
public:
explicit moneypunct_byname(const char*, size_t = 0);
};
}
char_type
Type of the first template argument.
string_type
Type of basic_string specialized on char_type, whose values are returned by some member functions.
explicit moneypunct(size_t refs = 0)
Constructs a moneypunct object. Calls locale::facet (refs).
The refs argument is set to the initial value of the object's reference count. A moneypunct object f constructed with (refs == 0) that is installed in one or more locale objects will be destroyed and the storage it occupies will be deallocated when the last locale object containing the facet is destroyed, as if by calling delete static_cast<locale::facet*>(&f). A moneypunct object constructed with (refs != 0) will not be destroyed by any locale objects in which it may have been installed.
explicit moneypunct_byname(const char* name,
size_t refs = 0);
Constructs a moneypunct_byname facet. Calls moneypunct (refs).
static locale::id id;
Unique identifier for this type of facet.
static const bool intl = Intl;
true for international representation, false otherwise.
The public members of the moneypunct and moneypunct_byname facets include an interface to protected members. Each public member function xxx() calls the corresponding protected virtual protected member function do_xxx(). For instance, the public member function decimal_point() function calls its protected cousin do_decimal_point().
string_type curr_symbol() const; charT decimal_point() const; int frac_digits() const; string grouping() const; pattern neg_format() const; string_type negative_sign() const; pattern pos_format() const; string_type positive_sign() const; charT thousands_sep() const;
Each public member function xxx() calls the corresponding protected do_xxx() function. The result of the call may be cached. Subsequent calls to the public function may return the cached result to avoid the expense of repeatedly calling the virtual function.
virtual string_type do_curr_symbol() const;
Returns a string to use as the currency symbol. In the C locale, the function returns the empty string. In named locales, the returned international string (in other words, when intl == true) typically conforms to the ISO 4217 standard. For example, the standard specifies that the US currency symbol for the Dollar is USD, and that the Japanese currency symbol for the Yen is JPY.
virtual charT do_decimal_point() const;
Returns the radix separator to use if fractional digits are allowed. See do_frac_digits(). In the C locale, the function returns the period ('.' and L'.').
virtual int do_frac_digits() const;
Returns the number of digits in the fractional part of the monetary representation. In the C locale, the function returns 0.
virtual string do_grouping() const;
Returns a string in which the numeric value of each character is used as an integer value to represent the number of digits in a particular grouping, starting with the rightmost group. A group is simply a sequence of digits between two adjacent thousands separators, or between the decimal point and the first thousands separator. Each group at a position greater than or equal to the size of the string gets the same value as the last element in the string. If a value is less than or equal to zero, or equal to CHAR_MAX, then the size of that group is unlimited. In the C locale, the function returns the empty string, indicating no grouping.
virtual string_type do_negative_sign() const;
A string to use as the negative sign. The first character of this string is placed in the position indicated by the format pattern. See do_neg_format(). The rest of the characters, if any, are placed after all other parts of the monetary value. In the C locale, the function returns the empty string.
virtual pattern do_neg_format() const; virtual pattern do_pos_format() const;
Returns a pattern object specifying the location of the various syntactic elements in a monetary representation. The enumeration values symbol, sign, and value appear exactly once in this pattern, with the remaining location taken by either none or space. none never occupies the first position in the pattern and space never occupies the first or the last position. Beyond these restrictions, elements may appear in any order. In the C locale, the functions return {symbol, sign, none, value}.
virtual string_type do_positive_sign() const;
A string to use as the positive sign for a monetary value. The first character of this string is placed in the position indicated by the format pattern. See do_pos_format(). The rest of the characters, if any, are placed after all other parts of the monetary value. In the C locale, the function returns the empty string.
virtual charT do_thousands_sep() const;
Returns the grouping separator. See do_grouping(). In the C locale, the function returns the comma (',' and L',').
#include <locale> // for locale
#include <iostream> // for cout, endl
#include <limits> // for numeric_limits
#include <examples.h>
int main ()
{
// Get a moneypunct facet from the global ("C") locale
const std::moneypunct<char, false> &mp =
std::use_facet<std::moneypunct<char, false>
>(std::locale ());
// expected values (see 7.11 of C99):
// Decimal point = ''
// Thousands seperator = ''
// Negative Sign = ""
// Digits after decimal = CHAR_MAX
// check to make sure the character returned from
decimal_point () and
// thousands_sep() are null characters so that the nulls are
not printed.
if ('\0' == mp.decimal_point ())
std::cout << "Decimal point = ''";
else
std::cout << "Decimal point = '" <<
mp.decimal_point () << "'";
if ('\0' == mp.thousands_sep ())
std::cout << "\nThousands seperator = ''";
else
std::cout << "\nThousands seperator = '" <<
mp.thousands_sep () << "'";
std::cout << "\nCurrency symbol = \"" << mp.curr_symbol
() << "\""
<< "\nNegative Sign = \"" <<
mp.negative_sign () << "\"";
// since the value of CHAR_MAX depends on the signedness of
char,
// if mp.frac_digits() equals CHAR_MAX print the string
"CHAR_MAX",
// otherwise print the actual value
if (std::numeric_limits<char>::max () == mp.frac_digits ())
std::cout << "\nDigits after decimal = CHAR_MAX\n";
else
std::cout << "\nDigits after decimal = " <<
mp.frac_digits () << '\n';
return 0;
}
Program Output:
Decimal point = ''
Thousands seperator = ''
Currency symbol = ""
Negative Sign = ""
Digits after decimal = CHAR_MAX
locale, Facets, money_put, money_get
ISO/IEC 14882:1998 -- International Standard for Information Systems -- Programming Language C++, Section 22.2.6.3