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

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

Format trait for the `e` character.

The `LowerExp` trait should format its output in scientific notation with a lower-case `e`.

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

# Examples

Basic usage with `i32`:

    let x = 42.0; // 42.0 is '4.2e1' in scientific notation

    assert_eq!(format!("{:e}", x), "4.2e1");

Implementing `LowerExp` on a type:

    use std::fmt;

    struct Length(i32);

    impl fmt::LowerExp 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);

## Required Methods

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

Formats the value using the given formatter.

## Implementors

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

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