84 lines
3.1 KiB
Markdown
84 lines
3.1 KiB
Markdown
[locale.numpunct.general]
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# 28 Text processing library [[text]](./#text)
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## 28.3 Localization library [[localization]](localization#locale.numpunct.general)
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### 28.3.4 Standard locale categories [[locale.categories]](locale.categories#locale.numpunct.general)
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#### 28.3.4.4 The numeric punctuation facet [[facet.numpunct]](facet.numpunct#locale.numpunct.general)
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#### 28.3.4.4.1 Class template numpunct [[locale.numpunct]](locale.numpunct#general)
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#### 28.3.4.4.1.1 General [locale.numpunct.general]
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[ð](#lib:numpunct)
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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);
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char_type decimal_point() const;
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char_type thousands_sep() const;
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string grouping() const;
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string_type truename() const;
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string_type falsename() const; static locale::id id; protected:~numpunct(); // virtualvirtual 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 boolvirtual string_type do_falsename() const; // for bool};}
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[1](#1)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/text.tex#L3137)
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numpunct<> specifies numeric punctuation[.](#1.sentence-1)
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The specializations
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required in Table [91](locale.category#tab:locale.category.facets "Table 91: Locale category facets") ([[locale.category]](locale.category "28.3.3.1.2.1 Type locale::category")),
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namely numpunct<wchar_t> and numpunct<char>,
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provide classic "C" numeric formats,
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i.e., they contain information
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equivalent to that contained in the "C" locale or
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their wide character counterparts as if obtained by a call to widen[.](#1.sentence-2)
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[2](#2)
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[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/text.tex#L3153)
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The syntax for number formats is as follows,
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where *digit* represents the radix set
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specified by the fmtflags argument value, and*thousands-sep* and *decimal-point* are the results of corresponding numpunct<charT> members[.](#2.sentence-1)
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Integer values have the format:
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intval :
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[*sign*](lex.fcon#nt:sign "5.13.4 Floating-point literals [lex.fcon]")opt units
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[*sign*](lex.fcon#nt:sign "5.13.4 Floating-point literals [lex.fcon]") :
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+
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-
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units :
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digits
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digits thousands-sep units
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digits :
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[*digit*](lex.name#nt:digit "5.11 Identifiers [lex.name]") digitsopt
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and floating-point values have:
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floatval :
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[*sign*](lex.fcon#nt:sign "5.13.4 Floating-point literals [lex.fcon]")opt units fractionalopt exponentopt
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[*sign*](lex.fcon#nt:sign "5.13.4 Floating-point literals [lex.fcon]")opt decimal-point digits exponentopt
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fractional :
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decimal-point digitsopt
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exponent :
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e [*sign*](lex.fcon#nt:sign "5.13.4 Floating-point literals [lex.fcon]")opt digits
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e :
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e
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E
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where the number of digits between *thousands-sep**s* is as specified by do_grouping()[.](#2.sentence-2)
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For parsing,
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if the *digits* portion contains no thousands-separators,
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no grouping constraint is applied[.](#2.sentence-3)
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