pub trait Octal {
// Required method
fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>;
}Available on crate feature
std only.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.