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.

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 · 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.

Implementors§

1.0.0 · source§

impl LowerHex for i8

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impl LowerHex for i16

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impl LowerHex for i32

1.0.0 · source§

impl LowerHex for i64

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impl LowerHex for i128

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impl LowerHex for isize

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impl LowerHex for u8

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impl LowerHex for u16

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impl LowerHex for u32

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impl LowerHex for u64

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impl LowerHex for u128

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impl LowerHex for usize

1.28.0 · source§

impl<T> LowerHex for NonZero<T>

1.74.0 · source§

impl<T: LowerHex> LowerHex for Saturating<T>

1.11.0 · source§

impl<T: LowerHex> LowerHex for Wrapping<T>

1.0.0 · source§

impl<T: ?Sized + LowerHex> LowerHex for &T

1.0.0 · source§

impl<T: ?Sized + LowerHex> LowerHex for &mut T