std::numpunct - cppreference.com (original) (raw)

| | | | | ---------------------------------------- | | | | 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-seps (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

Contents

• 1 Specializations
• 2 Nested types
• 3 Data members
• 4 Member functions
• 5 Protected member functions
• 6 Example
• 7 Defect reports
• 8 See also

[edit] Specializations

The standard library is guaranteed to provide the following specializations (they are required to be implemented by any locale object):

[edit] Nested types

[edit] Data members

[edit] Member functions

[edit] Protected member functions

| | provides the character to use as decimal point (virtual protected member function) [edit] | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | provides the character to use as thousands separator (virtual protected member function) [edit] | | | provides the numbers of digits between each pair of thousands separators (virtual protected member function) [edit] | | | provides the string to use as the name of the boolean true and false (virtual protected member function) [edit] |

[edit] Example

The following example changes the string representations of true and false:

#include #include   struct french_bool : std::numpunct { 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

[edit] Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit] See also

| | creates a numpunct facet for the named locale (class template) | | ----------------------------------------------------------------- |