# Trait collections::fmt::UpperExp 1.0.0 [−] [src]

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

Format trait for the `E` character.

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 `f32`:

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

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

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 = self.0;
            write!(f, "{}E1", val / 10)
        }
    }

    let l = Length(100);

    println!("l in scientific notation is: {:E}", l);Run

## Required Methods

### `fn fmt(&self, f: &mut Formatter) -> Result<(), Error>`

Formats the value using the given formatter.

## Implementors

- `impl UpperExp for f32`
- `impl UpperExp for f64`
- `impl<'a, T> UpperExp for &'a T where
  T: UpperExp + ?Sized,`
- `impl<'a, T> UpperExp for &'a mut T where
  T: UpperExp + ?Sized,`

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