Trait core::fmt::Binary

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

b formatting.

The Binary trait should format its output as a number in binary.

For primitive signed integers (i8 to i128, and isize), negative values are formatted as the two’s complement representation.

The alternate flag, #, adds a 0b 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 '101010' in binary

assert_eq!(format!("{x:b}"), "101010");
assert_eq!(format!("{x:#b}"), "0b101010");

assert_eq!(format!("{:b}", -16), "11111111111111111111111111110000");

Implementing Binary on a type:

use std::fmt;

struct Length(i32);

impl fmt::Binary for Length {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let val = self.0;

        fmt::Binary::fmt(&val, f) // delegate to i32's implementation
    }
}

let l = Length(107);

assert_eq!(format!("l as binary is: {l:b}"), "l as binary is: 1101011");

assert_eq!(
    // Note that the `0b` prefix added by `#` is included in the total width, so we
    // need to add two to correctly display all 32 bits.
    format!("l as binary is: {l:#034b}"),
    "l as binary is: 0b00000000000000000000000001101011"
);

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§

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impl Binary for i8

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impl Binary for i16

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impl Binary for i32

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impl Binary for i64

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impl Binary for i128

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impl Binary for isize

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impl Binary for u8

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impl Binary for u16

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impl Binary for u32

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impl Binary for u64

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impl Binary for u128

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impl Binary for usize

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impl<T> Binary for NonZero<T>

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impl<T: Binary> Binary for Saturating<T>

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impl<T: Binary> Binary for Wrapping<T>

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

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