Difference between revisions of "cpp/io/basic ostream/println"
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< cpp | io | basic ostream
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| − | {{title|println{{small|(std::ostream)}}}} | + | {{cpp/title|println{{small|(std::ostream)}}}} |
{{cpp/io/basic_ostream/navbar}} | {{cpp/io/basic_ostream/navbar}} | ||
{{dcl begin}} | {{dcl begin}} | ||
{{dcl header|ostream}} | {{dcl header|ostream}} | ||
| − | {{dcl|since=c++23|1= | + | {{dcl|num=1|since=c++23|1= |
template< class... Args > | template< class... Args > | ||
| − | + | void println( std::ostream& os, std::format_string<Args...> fmt, Args&&... args ); | |
| + | }} | ||
| + | {{dcla|num=2|since=c++26|1= | ||
| + | void println( std::ostream& os ); | ||
}} | }} | ||
{{dcl end}} | {{dcl end}} | ||
| Line 11: | Line 14: | ||
Formats {{tt|args}} according to the format string {{tt|fmt}} with appended {{c|'\n'}} (which means that each output ends with a new-line), and inserts the result into {{c|os}} stream. | Formats {{tt|args}} according to the format string {{tt|fmt}} with appended {{c|'\n'}} (which means that each output ends with a new-line), and inserts the result into {{c|os}} stream. | ||
| − | Equivalent to: | + | @1@ Equivalent to: |
{{box|{{ltt|cpp/io/basic_ostream/print|std::print}}{{c/core|(os, "{}\n", std::format(fmt, args...));}}}} | {{box|{{ltt|cpp/io/basic_ostream/print|std::print}}{{c/core|(os, "{}\n", std::format(fmt, args...));}}}} | ||
| + | |||
| + | @2@ Equivalent to: | ||
| + | {{box|{{ltt|cpp/io/basic_ostream/print|std::print}}{{c/core|(os, "\n");}}}} | ||
The behavior is undefined if {{c|std::formatter<Ti, char>}} does not meet the {{named req|BasicFormatter}} requirements for any {{tt|Ti}} in {{tt|Args}} (as required by {{c|std::make_format_args}}). | The behavior is undefined if {{c|std::formatter<Ti, char>}} does not meet the {{named req|BasicFormatter}} requirements for any {{tt|Ti}} in {{tt|Args}} (as required by {{c|std::make_format_args}}). | ||
| Line 30: | Line 36: | ||
===Notes=== | ===Notes=== | ||
| + | Although overload {{vl|2}} is added in C++26, all known implementations make it available in C++23 mode. | ||
| + | |||
{{ftm begin|std=1|value=1|comment=1}} | {{ftm begin|std=1|value=1|comment=1}} | ||
{{ftm|std=C++23|value=202207L|__cpp_lib_print|Formatted output}} | {{ftm|std=C++23|value=202207L|__cpp_lib_print|Formatted output}} | ||
Latest revision as of 20:53, 17 May 2024
| Defined in header <ostream>
|
||
| template< class... Args > void println( std::ostream& os, std::format_string<Args...> fmt, Args&&... args ); |
(1) | (since C++23) |
void println( std::ostream& os ); |
(2) | (since C++26) |
Formats args according to the format string fmt with appended '\n' (which means that each output ends with a new-line), and inserts the result into os stream.
1) Equivalent to:
std::print(os, "{}\n", std::format(fmt, args...));
2) Equivalent to:
std::print(os, "\n");
The behavior is undefined if std::formatter<Ti, char> does not meet the BasicFormatter requirements for any Ti in Args (as required by std::make_format_args).
Contents |
[edit] Parameters
| os | - | output stream to insert data into | ||||||||||||||||||||||||||||||||||||||||||||||
| fmt | - |
Each replacement field has the following format:
1) replacement field without a format specification
2) replacement field with a format specification
| ||||||||||||||||||||||||||||||||||||||||||||||
| args... | - | arguments to be formatted | ||||||||||||||||||||||||||||||||||||||||||||||
[edit] Return value
(none)
[edit] 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.
[edit] Notes
Although overload (2) is added in C++26, all known implementations make it available in C++23 mode.
| 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 |
[edit] Example
| This section is incomplete Reason: no example |
[edit] See also
| (C++23) |
outputs formatted representation of the arguments (function template) |
| (C++23) |
same as std::print except that each print is terminated by additional new line (function template) |
| (C++20) |
stores formatted representation of the arguments in a new string (function template) |
