std:: numpunct
|
Defined in header
<locale>
|
||
|
template
<
class
CharT
>
class numpunct ; |
||
The facet
std::numpunct
encapsulates numeric punctuation preferences. Stream I/O operations use
std::numpunct
through
std::num_get
and
std::num_put
for parsing numeric input and formatting numeric output.
The numbers that are supported by
std::numpunct
have the format described below. Here
digit
represents the radix set specified by the
fmtflags
argument value,
thousands-sep
and
decimal-point
are the results of
thousands_sep()
and
decimal_point()
functions respectively. The format of integer values is as follows:
integer ::= [sign] units sign ::= plusminus plusminus ::= '+' | '-' units ::= digits [thousands-sep units] digits ::= digit [digits]
The number of digits between the
thousand-sep
s (maximum size of
digits
) is specified by the result of
grouping()
.
The format of floating-point values is as follows:
floatval ::= [sign] units [decimal-point [digits]] [e [sign] digits] |
[sign] decimal-point digits [e [sign] digits]
e ::= 'e' | 'E'
Inheritance diagram
Specializations
The standard library is guaranteed to provide the following specializations (they are required to be implemented by any locale object ):
|
Defined in header
<locale>
|
|
| std :: numpunct < char > | provides equivalents of the "C" locale preferences |
| std :: numpunct < wchar_t > | provides wide character equivalents of the "C" locale preferences |
Nested types
| Type | Definition |
char_type
|
CharT
|
string_type
|
std:: basic_string < CharT > |
Data members
| Member | Description |
std::locale::id
id
[static]
|
the identifier of the facet |
Member functions
constructs a new
numpunct
facet
(public member function) |
|
destructs a
numpunct
facet
(protected member function) |
|
invokes
do_decimal_point
(public member function) |
|
invokes
do_thousands_sep
(public member function) |
|
invokes
do_grouping
(public member function) |
|
invokes
do_truename
or
do_falsename
(public member function) |
Protected member functions
|
[virtual]
|
provides the character to use as decimal point
(virtual protected member function) |
|
[virtual]
|
provides the character to use as thousands separator
(virtual protected member function) |
|
[virtual]
|
provides the numbers of digits between each pair of thousands separators
(virtual protected member function) |
|
[virtual]
|
provides the string to use as the name of the boolean
true
and
false
(virtual protected member function) |
Example
The following example changes the string representations of true and false :
#include <iostream> #include <locale> struct french_bool : std::numpunct<char> { string_type do_truename() const override { return "vrai"; } string_type do_falsename() const override { return "faux"; } }; int main() { std::cout << "default locale: " << std::boolalpha << true << ", " << false << '\n'; std::cout.imbue(std::locale(std::cout.getloc(), new french_bool)); std::cout << "locale with modified numpunct: " << std::boolalpha << true << ", " << false << '\n'; }
Output:
default locale: true, false locale with modified numpunct: vrai, faux
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 338 | C++98 |
the
sign
token allowed an optional whitespace following
+
or
-
|
removed the whitespace |
See also
|
creates a numpunct facet for the named locale
(class template) |