std::format_to

`<format>`
`template< class OutputIt, class... Args > OutputIt format_to( OutputIt out, std::format_string<Args...> fmt, Args&&... args );`	(1)	( C++20)
`template< class OutputIt, class... Args > OutputIt format_to( OutputIt out, std::wformat_string<Args...> fmt, Args&&... args );`	(2)	( C++20)
`template< class OutputIt, class... Args > OutputIt format_to( OutputIt out, const std::locale& loc, std::format_string<Args...> fmt, Args&&... args );`	(3)	( C++20)
`template< class OutputIt, class... Args > OutputIt format_to( OutputIt out, const std::locale& loc, std::wformat_string<Args...> fmt, Args&&... args );`	(4)	( C++20)

args fmt out. , loc , .

1) return std::vformat_to(out, fmt.str, std::make_format_args(args...));

2) return std::vformat_to(std::move(out), fmt.str, std::make_wformat_args(args...));

3) return std::vformat_to(out, loc, fmt.str, std::make_format_args(args...));

4) return std::vformat_to(std::move(out), loc, fmt.str, std::make_wformat_args(args...));

CharT char (1,3), wchar_t (2,4).

, OutputIt std::output_iterator<const CharT&>.

, OutputIt ( ) std::output_iterator<const CharT&> std::formatter<Ti, CharT> BasicFormatter Ti Args ( std::make_format_args std::make_wformat_args).

out

fmt

[edit]

, .

( { }), ,
{{ }}, { } ,
.

:


`{` - () `}`	(1)

`{` - () `:` - `}`	(2)

1)

2)

-		`args`, ; , . - . .
-		, std::formatter .

.
chrono chrono.
std::thread::id .
formatter.

args...

loc std::locale ,

.

, .

P2216R3, , . std::vformat_to.

#include <format>
#include <iostream>
#include <iterator>
#include <string>

auto main() -> int
{
    std::string buffer;

    std::format_to(
        std::back_inserter(buffer), //< OutputIt
        ", C++{}!\n",          //< fmt 
        "20");                      //< 
    std::cout << buffer;
    buffer.clear();

    std::format_to(
        std::back_inserter(buffer),       //< OutputIt
        ", {0}::{1}!{2}",           //< fmt 
        "std",                            //<  {0}
        "format_to()",                    //<  {1}
        "\n",                             //<  {2}
        " ()..."); //<  
    std::cout << buffer;

    std::wstring wbuffer;
    std::format_to(
        std::back_inserter(wbuffer),//< OutputIt 
        L", {2}::{1}!{0}",    //< fmt
        L"\n",                      //<  {0}
        L"format_to()",             //<  {1}
        L"std",                     //<  {2}
        L"... ..."             //<  
        L"...!");             //<  
    std::wcout << wbuffer;
}

:

, C++20!
, std::format_to()!
, std::format_to()!

C++:


WG	C++20	std::format_error
WG	C++20	, , (, , ),
WG	C++20		`basic_format_string`

format (C++20)	( ) []
format_to_n (C++20)	, ( ) []







(C++20)

(C++20)
(C++11)





(C++20)


/

(C++11)
(C++11)
(C++11)
(C++17)


format (C++20)
format_to (C++20)
format_to_n (C++20)
formatted_size (C++20)
vformat (C++20)
vformat_to (C++20)

formattable (C++23)

formatter (C++20)
range_formatter (C++23)
basic_format_parse_contextformat_parse_contextwformat_parse_context (C++20)(C++20)(C++20)
basic_format_contextformat_contextwformat_context (C++20)(C++20)(C++20)
range_format (C++23)
format_kind (C++23)

basic_format_arg (C++20)
basic_format_arg::handle (C++20)
basic_format_argsformat_argswformat_args (C++20)(C++20)(C++20)
basic_format_stringformat_stringwformat_string (C++20)(C++20)(C++20)
visit_format_arg (C++20) ( C++26)
make_format_argsmake_wformat_args (C++20)(C++20)

format_error (C++20)

cppreference.com

std::format_to