UpperHex in std::fmt - Rust
Description: `X` formatting.

## UpperHex

# Trait UpperHex

1.0.0 · Source

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

Expand description

`X` formatting.

The `UpperHex` trait should format its output as a number in hexadecimal, with `A` through `F` in upper 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 `UpperHex` on a type:

    use std::fmt;

    struct Length(i32);

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

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

    let l = Length(i32::MAX);

    assert_eq!(format!("l as hex is: {l:X}"), "l as hex is: 7FFFFFFF");

    assert_eq!(format!("l as hex is: {l:#010X}"), "l as hex is: 0x7FFFFFFF");

## 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 UpperHex for i8

1.0.0 · Source§

### impl UpperHex for i16

1.0.0 · Source§

### impl UpperHex for i32

1.0.0 · Source§

### impl UpperHex for i64

1.0.0 · Source§

### impl UpperHex for i128

1.0.0 · Source§

### impl UpperHex for isize

1.0.0 · Source§

### impl UpperHex for u8

1.0.0 · Source§

### impl UpperHex for u16

1.0.0 · Source§

### impl UpperHex for u32

1.0.0 · Source§

### impl UpperHex for u64

1.0.0 · Source§

### impl UpperHex for u128

1.0.0 · Source§

### impl UpperHex for usize

1.0.0 · Source§

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

1.0.0 · Source§

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

1.28.0 · Source§

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

1.74.0 · Source§

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

1.11.0 · Source§

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