pub trait Display {
// Required method
fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>;
}Expand description
Format trait for an empty format, {}.
Implementing this trait for a type will automatically implement the
ToString trait for the type, allowing the usage
of the .to_string() method. Prefer implementing
the Display trait for a type, rather than ToString.
Display is similar to Debug, but Display is for user-facing
output, and so cannot be derived.
For more information on formatters, see the module-level documentation.
§Internationalization
Because a type can only have one Display implementation, it is often preferable
to only implement Display when there is a single most “obvious” way that
values can be formatted as text. This could mean formatting according to the
“invariant” culture and “undefined” locale, or it could mean that the type
display is designed for a specific culture/locale, such as developer logs.
If not all values have a justifiably canonical textual format or if you want
to support alternative formats not covered by the standard set of possible
formatting traits, the most flexible approach is display adapters: methods
like str::escape_default or Path::display which create a wrapper
implementing Display to output the specific display format.
§Examples
Implementing Display on a type:
use std::fmt;
struct Point {
x: i32,
y: i32,
}
impl fmt::Display for Point {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "({}, {})", self.x, self.y)
}
}
let origin = Point { x: 0, y: 0 };
assert_eq!(format!("The origin is: {origin}"), "The origin is: (0, 0)");Required Methods§
1.0.0 · Sourcefn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>
fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>
Formats the value using the given formatter.
§Errors
This function should return Err if, and only if, the provided Formatter returns Err.
String formatting is considered an infallible operation; this function only
returns a Result because writing to the underlying stream might fail and it must
provide a way to propagate the fact that an error has occurred back up the stack.
§Examples
use std::fmt;
struct Position {
longitude: f32,
latitude: f32,
}
impl fmt::Display for Position {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "({}, {})", self.longitude, self.latitude)
}
}
assert_eq!(
"(1.987, 2.983)",
format!("{}", Position { longitude: 1.987, latitude: 2.983, }),
);Implementors§
impl Display for AsciiChar
impl Display for Infallible
impl Display for IpAddr
impl Display for SocketAddr
impl Display for GetManyMutError
impl Display for bool
impl Display for char
impl Display for f32
impl Display for f64
impl Display for i8
impl Display for i16
impl Display for i32
impl Display for i64
impl Display for i128
impl Display for isize
impl Display for !
impl Display for str
impl Display for u8
impl Display for u16
impl Display for u32
impl Display for u64
impl Display for u128
impl Display for usize
impl Display for LayoutError
impl Display for AllocError
impl Display for TryFromSliceError
impl Display for core::ascii::EscapeDefault
impl Display for BorrowError
impl Display for BorrowMutError
impl Display for CharTryFromError
impl Display for ParseCharError
impl Display for DecodeUtf16Error
impl Display for core::char::EscapeDebug
impl Display for core::char::EscapeDefault
impl Display for core::char::EscapeUnicode
impl Display for ToLowercase
impl Display for ToUppercase
impl Display for TryFromCharError
impl Display for FromBytesUntilNulError
impl Display for FromBytesWithNulError
impl Display for Ipv4Addr
impl Display for Ipv6Addr
Writes an Ipv6Addr, conforming to the canonical style described by RFC 5952.