std::vprint_nonunicode, std::vprint_nonunicode_buffered

 

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print (C++23)

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vprint_unicodevprint_unicode_buffered (C++23)(C++23)

vprint_nonunicodevprint_nonunicode_buffered (C++23)(C++23)

 

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 }. For basic types and standard string types, the format specification is interpreted as standard format specification. For chrono types, the format specification is interpreted as chrono format specification. For range types, the format specification is interpreted as range format specification. For std::pair and std::tuple, the format specification is interpreted as tuple format specification. For std::thread::id and std::stacktrace_entry, see thread id format specification and stacktrace entry format specification. For std::basic_stacktrace, no format specifier is allowed. (since C++23) For std::filesystem::path, see path format specification. (since C++26) For other formattable types, the format specification is determined by user-defined formatter specializations.
args	-	arguments to be formatted

Exceptions

• std::bad_alloc on allocation failure.
• std::system_error, if writing to the stream fails.
• Propagates any exception thrown by used formatters, e.g. std::format_error.

Notes

Feature-test macro	Value	Std	Feature
__cpp_lib_print	202207L	(C++23)	Formatted output
	202403L	(C++26) (DR23)	Unbuffered formatted output
	202406L	(C++26) (DR23)	Enabling unbuffered formatted output for more formattable types
__cpp_lib_format	202207L	(C++23)	Exposing std::basic_format_string

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
P3107R5	C++23	printing operations were always buffered	provides unbuffered printing operations
P3235R3	C++23	the names of the functions added by P3107R5 were misleading	changed the function names

See also

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