# Trait Binary

1.36.0 · Source

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

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<(), 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.

## Implementors§

1.0.0 · Source§

### impl Binary for i8

1.0.0 · Source§

### impl Binary for i16

1.0.0 · Source§

### impl Binary for i32

1.0.0 · Source§

### impl Binary for i64

1.0.0 · Source§

### impl Binary for i128

1.0.0 · Source§

### impl Binary for isize

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### impl Binary for u8

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### impl Binary for u16

1.0.0 · Source§

### impl Binary for u32

1.0.0 · Source§

### impl Binary for u64

1.0.0 · Source§

### impl Binary for u128

1.0.0 · Source§

### impl Binary for usize

1.0.0 · Source§

### impl<T> Binary for &T
where T: Binary + ?Sized,

1.0.0 · Source§

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

1.28.0 · Source§

### impl<T> Binary for NonZero<T>
where T: ZeroablePrimitive + Binary,

1.74.0 · Source§

### impl<T> Binary for Saturating<T>
where T: Binary,

1.11.0 · Source§

### impl<T> Binary for Wrapping<T>
where T: Binary,