std::vprint...td::ostream)(3)

💖 NAME 💖

Okay bestie, welcome to the C++ Standard Libary glow-up of this page — the manual slot is std::vprint...td::ostream)(3), and the main character is std::vprint_unicode(std::ostream). Official NAME line, no cap:

std::vprint_unicode(std::ostream) - std::vprint_unicode(std::ostream)

✨ Synopsis ✨

Here's the header and signature, copied exactly so your compiler and your group chat agree:

Defined in header <ostream>
void vprint_unicode( std::ostream& os, std::string_view fmt,
                     std::format_args args );

(since C++23) — yes, this one is C++23-coded 💅.

It behaves as a FormattedOutputFunction (except that some details of error reporting differ), and the steps are:

• First, the function constructs and checks the sentry object.
• Then it initializes an automatic variable as if by std::string out = std::vformat(os.getloc(), fmt, args);.
• Finally, it inserts the character sequence [out.begin(), out.end()) into os. That means: if os refers to a terminal capable of displaying Unicode, it writes out to this terminal using the native Unicode API. Otherwise, it writes unmodified out to the os.

🌸 Parameters 🌸

• os — output stream to insert data into.
• 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-ids 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 format-spec, the vibe check goes like this:

• 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.

(since C++23)

• 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.
• 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.

🎀 Return value 🎀

(none) — that's it, bestie. No return value era 💖.

🔥 Exceptions 🔥

• std::bad_alloc on allocation failure.
• Propagate any exception thrown by any formatter, e.g. std::format_error, without regard to the value of os.exceptions() and without turning on ios_base::badbit in the error state of os.
• May throw ios_base::failure caused by os.setstate(ios_base::badbit) which is called if an insertion into os fails.

🦋 Notes 🦋

If invoking the native Unicode API requires transcoding, the invalid code units are substituted with U+FFFD REPLACEMENT CHARACTER (see "The Unicode Standard Version 14.0 - Core Specification", Chapter 3.9).

Feature-test macro tea ☕:

Feature-test macro  Value    Std                Feature
__cpp_lib_print    202207L (C++23) Formatted output
__cpp_lib_format   202207L (C++23) Exposing std::basic_format_string

⭐ Example ⭐

This section is incomplete. Reason: no example.

👑 See also 👑

• vprint_nonunicode(std::ostream) (C++23) — outputs character data using type-erased argument representation (function).
• print(std::ostream) (C++23) — outputs formatted representation of the arguments (function template).
• operator<<(std::basic_ostream) — inserts character data or insert into rvalue stream (function template).
• vprint_unicode (C++23) — prints to Unicode capable stdout or a file stream using type-erased argument representation (function).
• vprint_unicode_locking (C++23) — prints to Unicode capable stdout or a file stream using type-erased argument representation (function).
• format (C++20) — stores formatted representation of the arguments in a new string (function template).

🌈 External links 🌈

1. Unicode
2. The Unicode Standard Version 14.0 - Core Specification

🍓 Category 🍓

• Todo no example

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And that's the whole page, bestie — source/version: http://cppreference.com, date: 2024.06.10, footer manual name: std::vprint...td::ostream)(3). Go slay your Unicode output 💅✨