Difference between revisions of "cpp/io/println"
From cppreference.com
m (fmt) |
m (added C++26 std::println();) |
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| Line 12: | Line 12: | ||
template< class... Args > | template< class... Args > | ||
void println( std::format_string<Args...> fmt, Args&&... args ); | void println( std::format_string<Args...> fmt, Args&&... args ); | ||
| + | }} | ||
| + | {{dcl|num=3|since=c++26|1= | ||
| + | void println( std::FILE* stream ); | ||
| + | }} | ||
| + | {{dcl|num=4|since=c++26|1= | ||
| + | void println(); | ||
}} | }} | ||
{{dcl end}} | {{dcl end}} | ||
| Line 21: | Line 27: | ||
@2@ same as {{v|1}} when {{c|stream}} is equal to the standard C output stream {{lc|stdout}}, i.e. | @2@ same as {{v|1}} when {{c|stream}} is equal to the standard C output stream {{lc|stdout}}, i.e. | ||
{{c|std::println(stdout, fmt, args...);}} | {{c|std::println(stdout, fmt, args...);}} | ||
| + | |||
| + | @3@ Equivalent to: {{c|std::print(stream, "\n");}} | ||
| + | |||
| + | @4@ same as {{v|3}} when {{c|stream}} is equal to the standard C output stream {{lc|stdout}}, i.e. {{c|std::println(stdout);}} | ||
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 57: | Line 67: | ||
std::print("word"); | std::print("word"); | ||
| − | std::println( | + | std::println(); // valid since C++26; same effect as std::print("\n"); |
} | } | ||
|output= | |output= | ||
Revision as of 05:07, 23 March 2024
| Defined in header <print>
|
||
| template< class... Args > void println( std::FILE* stream, |
(1) | (since C++23) |
| template< class... Args > void println( std::format_string<Args...> fmt, Args&&... args ); |
(2) | (since C++23) |
| void println( std::FILE* stream ); |
(3) | (since C++26) |
| void println(); |
(4) | (since C++26) |
Format args according to the format string fmt with appended '\n' (which means that each output ends with a new-line), and print the result to a stream.
1) Equivalent to: std::print(stream, "{}\n", std::format(fmt, args...));
2) same as (1) when stream is equal to the standard C output stream stdout, i.e.
std::println(stdout, fmt, args...);
3) Equivalent to: std::print(stream, "\n");
4) same as (3) when stream is equal to the standard C output stream stdout, i.e. std::println(stdout);
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 |
Parameters
| stream | - | output file stream to write to | ||||||||||||||||||||||||||||||||||||||||||||||
| 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 | ||||||||||||||||||||||||||||||||||||||||||||||
Return value
(none)
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 |
__cpp_lib_format |
202207L | (C++23) | Exposing std::basic_format_string |
Example
Run this code
#include <print> int main() { // Each call to std::println ends with new-line std::println("Please"); std::println("enter"); std::print("pass"); std::print("word"); std::println(); // valid since C++26; same effect as std::print("\n"); }
Output:
Please enter password
See also
| (C++23) |
prints to stdout or a file stream using formatted representation of the arguments (function template) |
| (C++23) |
outputs formatted representation of the arguments with appended '\n' (function template) |
| (C++20) |
stores formatted representation of the arguments in a new string (function template) |
| (C++11) |
prints formatted output to stdout, a file stream or a buffer (function) |
