UpperExp in alloc::fmt - Rust
Description: `E` formatting.

## UpperExp

# Trait UpperExp

1.36.0 · Source

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

Expand description

`E` formatting.

The `UpperExp` trait should format its output in scientific notation with an upper-case `E`.

For more information on formatters, see the module-level documentation.

## §Examples

Basic usage with `f64`:

    let x = 42.0; // 42.0 is '4.2E1' in scientific notation

    assert_eq!(format!("{x:E}"), "4.2E1");

Implementing `UpperExp` on a type:

    use std::fmt;

    struct Length(i32);

    impl fmt::UpperExp for Length {
        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
            let val = f64::from(self.0);
            fmt::UpperExp::fmt(&val, f) // delegate to f64's implementation
        }
    }

    let l = Length(100);

    assert_eq!(
        format!("l in scientific notation is: {l:E}"),
        "l in scientific notation is: 1E2"
    );

    assert_eq!(
        format!("l in scientific notation is: {l:05E}"),
        "l in scientific notation is: 001E2"
    );

## 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 UpperExp for f16

Available on non-`target_has_reliable_f16` only.
1.0.0 · Source§

### impl UpperExp for f32

1.0.0 · Source§

### impl UpperExp for f64

1.42.0 · Source§

### impl UpperExp for i8

1.42.0 · Source§

### impl UpperExp for i16

1.42.0 · Source§

### impl UpperExp for i32

1.42.0 · Source§

### impl UpperExp for i64

1.42.0 · Source§

### impl UpperExp for i128

1.42.0 · Source§

### impl UpperExp for isize

1.42.0 · Source§

### impl UpperExp for u8

1.42.0 · Source§

### impl UpperExp for u16

1.42.0 · Source§

### impl UpperExp for u32

1.42.0 · Source§

### impl UpperExp for u64

1.42.0 · Source§

### impl UpperExp for u128

1.42.0 · Source§

### impl UpperExp for usize

1.0.0 · Source§

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

1.0.0 · Source§

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

1.84.0 · Source§

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