core::writeln! 1.0.0
[−]
[src]
macro_rules! writeln { ($dst:expr, $fmt:expr) => { ... }; ($dst:expr, $fmt:expr, $($arg:tt)*) => { ... }; }
1.0.0
Write formatted data into a buffer, with appending a newline.
On all platforms, the newline is the LINE FEED character (\n
/U+000A
) alone
(no additional CARRIAGE RETURN (\r
/U+000D
).
This macro accepts any value with write_fmt
method as a writer, a format string, and a list
of arguments to format.
write_fmt
method usually comes from an implementation of std::fmt::Write
or
std::io::Write
traits. These are sometimes called 'writers'.
Passed arguments will be formatted according to the specified format string and the resulting string will be passed to the writer.
See std::fmt
for more information on format syntax.
Return value is completely dependent on the 'write_fmt' method.
Common return values are: Result
, io::Result
Examples
fn main() { 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()); }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());