std::wprint / std::wprintln

void vprint_unicode(wostream& os, wstring_view fmt, wformat_args args);
void vprint_nonunicode(wostream& os, wstring_view fmt, wformat_args args);

Effects: Behaves as a formatted output function of os, except that:

• Failure to generate output is reported as specified below, and
• Any exception thrown by the call to vformat is propagated without regard to the value of os.exceptions() and without turning on ios_base::badbit in the error state of os.

After constructing a sentry object, the function initialises an automatic variable via:

wstring out = vformat(os.getloc(), fmt, args);

If the function is vprint_unicode and os is a stream that refers to a terminal capable of displaying Unicode (determined in an implementation-defined manner), it writes out to the terminal using the native Unicode API; if out contains invalid code units, the behaviour is undefined and implementations are encouraged to diagnose it. If the native Unicode API is used, the function flushes os before writing out. Otherwise (if os is not such a stream or the function is vprint_nonunicode), inserts the character sequence [out.begin(), out.end()) into os. If writing to the terminal or inserting into os fails, calls os.setstate(ios_base::badbit) (which may throw ios_base::failure).

Recommended practice: For vprint_unicode, if invoking the native Unicode API requires transcoding, implementations should substitute invalid code units with u+fffd replacement character per the Unicode Standard, Chapter 3.9 u+fffd Substitution in Conversion.

void vprint_unicode(FILE* stream, wstring_view fmt, wformat_args args);
void vprint_nonunicode(FILE* stream, wstring_view fmt, wformat_args args);

Preconditions: stream is a valid pointer to an output C wide stream.

Effects: The function initialises an automatic variable via:

wstring out = vformat(fmt, args);

If stream refers to a terminal capable of displaying Unicode, writes out to the terminal using the native Unicode API; if out contains invalid code units, the behaviour is undefined and implementations are encouraged to diagnose it. Otherwise writes out to stream unchanged. If the native Unicode API is used, the function flushes stream before writing out.

• Note 1: On POSIX and Windows, stream referring to a terminal means that isatty(fileno(stream)) and GetConsoleMode(_get_osfhandle(_fileno(stream)), ...) return nonzero.
• Note 2: On Windows, the native Unicode API is WriteConsoleW.

Throws: Any exception thrown by the call to vformat. system_error if writing to the terminal or stream fails. May throw bad_alloc.

Recommended practice: If invoking the native Unicode API requires transcoding, implementations should substitute invalid code units with u+fffd replacement character per the Unicode Standard, Chapter 3.9 u+fffd Substitution in Conversion.

Templates

template<class... Args>
          void print(wformat_string<Args...> fmt, Args&&... args);
          

Effects: Equivalent to:

print(stdout, fmt, std::forward<Args>(args)...);

template<class... Args>
          void print(FILE* stream, wformat_string<Args...> fmt, Args&&... args);
          

Effects: If the ordinary literal encoding is UTF-8, UTF-16 or UTF-32, equivalent to:

vprint_unicode(stream, fmt.str, make_wformat_args(std::forward<Args>(args)...));

Otherwise, equivalent to:

vprint_nonunicode(stream, fmt.str, make_wformat_args(std::forward<Args>(args)...));

template<class... Args>
          void println(wformat_string<Args...> fmt, Args&&... args);
          

Effects: Equivalent to:

println(stdout, fmt, std::forward<Args>(args)...);

template<class... Args>
          void println(FILE* stream, wformat_string<Args...> fmt, Args&&... args);
          

Effects: Equivalent to:

print(stream, L"{}\n", format(fmt, std::forward<Args>(args)...));

void vprint_unicode(wstring_view fmt, wformat_args args);
          

Effects: Equivalent to:

vprint_unicode(stdout, fmt, args);