std::vprint_nonunicode, std::vprint_nonunicode_buffered
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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)
std::string_view fmt, std::format_args args );
void vprint_nonunicode_buffered
( std::FILE * stream, std::string_view fmt, std::format_args args );
(2)
(since C++23)
( std::FILE * stream, std::string_view fmt, std::format_args args );
void vprint_nonunicode_buffered
( std::string_view fmt, std::format_args args );
(3)
(since C++23)
( std::string_view fmt, std::format_args args );
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));.
std::vprint_nonunicode(stream, "{}", std::make_format_args (out));.
3) Equivalent to std::vprint_nonunicode_buffered(stdout, fmt, args).
After writing characters to the output stream, establishes an observable checkpoint.
(since C++26)[edit] Parameters
stream
-
output file stream to write to
fmt
-
an object that represents the format string. The format string consists of
args
-
arguments to be formatted
- 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++26)
- For other formattable types, the format specification is determined by user-defined
formatterspecializations.
[edit] 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 .
[edit] 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 |
[edit] Example
This section is incomplete
Reason: no example
Reason: no example
[edit] 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 |
[edit] See also
prints to Unicode capable stdout or a file stream using type-erased argument representation
(function) [edit]
(function) [edit]