Trait core::fmt::LowerHex

1.0.0 · source ·
``````pub trait LowerHex {
// Required method
fn fmt(&self, f: &mut Formatter<'_>) -> Result;
}``````
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.

§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 · source

fn fmt(&self, f: &mut Formatter<'_>) -> Result

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.

1.0.0 · source§

1.0.0 · source§

1.0.0 · source§

1.0.0 · source§

1.0.0 · source§

1.0.0 · source§

1.0.0 · source§

1.0.0 · source§

1.0.0 · source§

1.0.0 · source§

1.0.0 · source§

1.0.0 · source§

1.28.0 · source§

1.74.0 · source§

1.11.0 · source§

1.0.0 · source§

1.0.0 · source§