std::vprint_nonunicode, std::vprint_nonunicode_buffered

From cppreference.com
< cpp‎ | io
Defined in header <print>
void vprint_nonunicode( std::FILE* stream,
                        std::string_view fmt, std::format_args args );
(1) (since C++23)
void vprint_nonunicode_buffered( std::FILE* stream,
                                 std::string_view fmt, std::format_args args );
(2) (since C++23)
void vprint_nonunicode_buffered( std::string_view fmt, std::format_args args );
(3) (since C++23)

Format args according to the format string fmt, and writes the result to the output stream.

1) While holding the lock on stream, writes the character representation of formatting arguments provided by args formatted according to specifications given in fmt to stream.
If stream is not a valid pointer to an output C stream, the behavior is undefined.
2) Equivalent to: std::string out = std::vformat(fmt, args);
std::vprint_nonunicode(stream, "{}", std::make_format_args(out));
3) Equivalent to: std::vprint_nonunicode_buffered(stdout, fmt, args).

Parameters

stream - output file stream to write to
fmt - an object that represents the format string. The format string consists of
  • ordinary characters (except { and }), which are copied unchanged to the output,
  • escape sequences {{ and }}, which are replaced with { and } respectively in the output, and
  • replacement fields.

Each replacement field has the following format:

{ arg-id (optional) } (1)
{ arg-id (optional) : format-spec } (2)
1) replacement field without a format specification
2) replacement field with a format specification
arg-id - specifies the index of the argument in args whose value is to be used for formatting; if it is omitted, the arguments are used in order.

The arg-id s in a format string must all be present or all be omitted. Mixing manual and automatic indexing is an error.

format-spec - the format specification defined by the std::formatter specialization for the corresponding argument. Cannot start with }.

(since C++23)
(since C++26)
  • For other formattable types, the format specification is determined by user-defined formatter specializations.
args - arguments to be formatted

Exceptions

Notes

Feature-test macro Value Std Feature
__cpp_lib_print 202207L (C++23) Formatted output
202403L (C++26)
(DR23)
Formatted output with stream locking
202406L (C++26)
(DR23)
Enabling nonlocking formatter optimization for more formattable types
__cpp_lib_format 202207L (C++23) Exposing std::basic_format_string

Example

See also

prints to Unicode capable stdout or a file stream using type-erased argument representation
(function)
outputs character data using type-erased argument representation
(function)
(C++23)
prints to stdout or a file stream using formatted representation of the arguments
(function template)
(C++20)
stores formatted representation of the arguments in a new string
(function template)