| Defined in header <locale> | ||||
|---|---|---|---|---|
|
Class std::num_put encapsulates the rules for formatting numeric values as strings. Specifically, the types bool, long, unsigned long, long long, unsigned long long, double, long double, void*, and of all types implicitly convertible to these (such as int or float) are supported. The standard formatting output operators (such as cout << n;) use the std::num_put facet of the I/O stream's locale to generate text representation of numbers.
Inheritance diagram.
Type requirements
- OutputIt must meet the requirements of OutputIterator. |
Specializations
Two standalone (locale-independent) full specializations and two partial specializations are provided by the standard library:
| Defined in header <locale> | |
|---|---|
std::num_put<char> | creates narrow string representations of numbers |
std::num_put<wchar_t> | creates wide string representations of numbers |
std::num_put<char, OutputIt> | creates narrow string representations of numbers using custom output iterator |
std::num_put<wchar_t, OutputIt> | creates wide string representations of numbers using custom output iterator |
In addition, every locale object constructed in a C++ program implements its own (locale-specific) versions of these specializations.
Member types
| Member type | Definition |
|---|---|
char_type | CharT |
iter_type | OutputIt |
Member functions
| constructs a new num_put facet (public member function) | |
| (destructor)
| destructs a num_put facet (protected member function) |
invokes do_put (public member function) |
Protected member functions
| [virtual] | formats a number and writes to output stream (virtual protected member function) |
Member objects
| static std::locale::id id | id of the locale (public member object) |
Example
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | #include <iostream>#include <locale>#include <string>#include <iterator> int main(){ double n = 1234567.89; std::cout.imbue(std::locale("de_DE")); std::cout << "Direct conversion to string:\n" << std::to_string(n) << '\n' << "Output using a german locale:\n" << std::fixed << n << '\n' << "Output using an american locale:\n"; // use the facet directly std::cout.imbue(std::locale("en_US.UTF-8")); auto& f = std::use_facet<std::num_put<char>>(std::cout.getloc()); f.put(std::ostreambuf_iterator<char>(std::cout), std::cout, ' ', n); std::cout << '\n';} |
Output:
1 2 3 4 5 6 | Direct conversion to string:1234567.890000Output using a german locale:1.234.567,890000Output using an american locale:1,234,567.890000 |
See also
| defines numeric punctuation rules (class template) | |
| parses numeric values from an input character sequence (class template) | |
| (C++11) | converts an integral or floating point value to string (function) |
| (C++11) | converts an integral or floating point value to wstring (function) |
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