pub(crate) trait LowerHex {
// Required method
fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>;
}Expand description
x formatting.
The LowerHex trait should format its output as a number in hexadecimal, with a through f
in lower case.
For primitive signed integers (i8 to i128, and isize),
negative values are formatted as the two’s complement representation.
The alternate flag, #, adds a 0x in front of the output.
For more information on formatters, see the module-level documentation.
§Examples
Basic usage with i32:
let y = 42; // 42 is '2a' in hex
assert_eq!(format!("{y:x}"), "2a");
assert_eq!(format!("{y:#x}"), "0x2a");
assert_eq!(format!("{:x}", -16), "fffffff0");Implementing LowerHex on a type:
use std::fmt;
struct Length(i32);
impl fmt::LowerHex for Length {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let val = self.0;
fmt::LowerHex::fmt(&val, f) // delegate to i32's implementation
}
}
let l = Length(9);
assert_eq!(format!("l as hex is: {l:x}"), "l as hex is: 9");
assert_eq!(format!("l as hex is: {l:#010x}"), "l as hex is: 0x00000009");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.