pub trait Octal {
// Required method
fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>;
}Expand description
o formatting.
The Octal trait should format its output as a number in base-8.
For primitive signed integers (i8 to i128, and isize),
negative values are formatted as the two’s complement representation.
The alternate flag, #, adds a 0o in front of the output.
For more information on formatters, see the module-level documentation.
§Examples
Basic usage with i32:
let x = 42; // 42 is '52' in octal
assert_eq!(format!("{x:o}"), "52");
assert_eq!(format!("{x:#o}"), "0o52");
assert_eq!(format!("{:o}", -16), "37777777760");Implementing Octal on a type:
use std::fmt;
struct Length(i32);
impl fmt::Octal for Length {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let val = self.0;
fmt::Octal::fmt(&val, f) // delegate to i32's implementation
}
}
let l = Length(9);
assert_eq!(format!("l as octal is: {l:o}"), "l as octal is: 11");
assert_eq!(format!("l as octal is: {l:#06o}"), "l as octal is: 0o0011");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.
Dyn Compatibility§
This trait is dyn compatible.
In older versions of Rust, dyn compatibility was called "object safety".