Namespaces
Variants
Views
Actions

std::num_put

From cppreference.com
< cpp‎ | locale
Revision as of 18:11, 2 November 2012 by P12bot (Talk | contribs)

Template:ddcl list begin <tr class="t-dsc-header">

<td>
Defined in header <locale>
</td>

<td></td> <td></td> <tr class="t-dcl ">

<td class="t-dcl-nopad">
template<

    class CharT,
    class OutputIt = std::ostreambuf_iterator<CharT>

> class num_put;
</td>

<td class="t-dcl-nopad"> </td> <td class="t-dcl-nopad"> </td> </tr> Template:ddcl list end

Class std::num_put encapsulates the rules for formatting values of type 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), as strings. 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.

cpp/locale/locale/facetstd-num put-inheritance.svg
About this image

Inheritance diagram

Contents

Type requirements

-
OutputIt must meet the requirements of OutputIterator.

Specializations

Two specializations and two partial specializations are provided by the standard library and are implemented by all locale objects created in a C++ program:

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

Member types

Member type Definition
char_type CharT
iter_type OutputIt

Member functions

constructs a new num_put facet
(public member function)
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

#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:

Direct conversion to string:
1234567.890000
Output using a german locale:
1.234.567,890000
Output using an american locale:
1,234,567.890000

See also

Template:cpp/locale/dcl list numpunctTemplate:cpp/locale/dcl list num getTemplate:cpp/string/basic string/dcl list to stringTemplate:cpp/string/basic string/dcl list to wstring