Macro core::writeln 1.0.0
[−]
[src]
macro_rules! writeln { ($dst:expr, $fmt:expr) => { ... }; ($dst:expr, $fmt:expr, $($arg:tt)*) => { ... }; }
Write formatted data into a buffer, with a newline appended.
On all platforms, the newline is the LINE FEED character (\n
/U+000A
) alone
(no additional CARRIAGE RETURN (\r
/U+000D
).
This macro accepts a 'writer' (any value with a write_fmt
method), a format string, and a
list of arguments to format.
The write_fmt
method usually comes from an implementation of std::fmt::Write
or std::io::Write
traits. The term 'writer' refers to an implementation of one of
these two traits.
Passed arguments will be formatted according to the specified format string and the resulting string will be passed to the writer, along with the appended newline.
See std::fmt
for more information on format syntax.
write!
returns whatever the 'write_fmt' method returns.
Common return values include: fmt::Result
, io::Result
Examples
use std::io::Write; let mut w = Vec::new(); writeln!(&mut w, "test").unwrap(); writeln!(&mut w, "formatted {}", "arguments").unwrap(); assert_eq!(&w[..], "test\nformatted arguments\n".as_bytes());Run