[locale.numpunct] (original) (raw)

28 Text processing library [text]

28.3 Localization library [localization]

28.3.4 Standard locale categories [locale.categories]

28.3.4.4.1 Class template numpunct [locale.numpunct]

28.3.4.4.1.1 General [locale.numpunct.general]

namespace std { template<class charT> class numpunct : public locale::facet { public: using char_type = charT;using string_type = basic_string<charT>;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 char_type do_decimal_point() const;virtual char_type do_thousands_sep() const;virtual string do_grouping() const;virtual string_type do_truename() const; virtual string_type do_falsename() const; };}

numpunct<> specifies numeric punctuation.

The specializations required in Table 89 ([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:

intval :
sign units

units :
digits
digits thousands-sep units

digits :
digit digits

and floating-point values have:

floatval :
sign units fractional exponent
sign decimal-point digits exponent

fractional :
decimal-point digits

exponent :
e sign digits

e :
e
E

where the number of digits between thousands-sep _s_is as specified by do_grouping().

For parsing, if the digits portion contains no thousands-separators, no grouping constraint is applied.

28.3.4.4.1.2 Members [facet.numpunct.members]

char_type decimal_point() const;

Returns: do_decimal_point().

char_type thousands_sep() const;

Returns: do_thousands_sep().

string_type truename() const; string_type falsename() const;

Returns: do_truename()ordo_falsename(), respectively.

28.3.4.4.1.3 Virtual functions [facet.numpunct.virtuals]

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','.

string do_grouping() const;

Returns: A string vec used as a vector of integer values, in which each element vec[i] represents the number of digits[226](#footnote-226 "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".")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".