std::num_put(3) | C++ Standard Libary | std::num_put(3) |
NAME¶
std::num_put - std::num_put
Synopsis¶
Defined in header <locale>
template<
class CharT,
class OutputIt = std::ostreambuf_iterator<CharT>
> class num_put;
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.
std-num put-inheritance.svg
Inheritance diagram
Type requirements¶
-
OutputIt must meet the requirements of LegacyOutputIterator.
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¶
constructor constructs a new num_put facet
(public member function)
destructor destructs a num_put facet
(protected member function)
put invokes do_put
(public member function)
Protected member functions¶
do_put formats a number and writes to output stream
[virtual] (virtual protected member function)
Member objects¶
static std::locale::id id id of the locale
(public member object)
Example¶
// Run this code
#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¶
numpunct defines numeric punctuation rules
(class template)
num_get parses numeric values from an input character sequence
(class template)
to_string converts an integral or floating point value to string
(C++11) (function)
to_wstring converts an integral or floating point value to wstring
(C++11) (function)
2022.07.31 | http://cppreference.com |