LowerExp in alloc::fmt - Rust
Description: `e` formatting.
Keywords: rust, rustlang, rust-lang, LowerExp

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

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

Expand description

`e` formatting.

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 `f64`:

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

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

Run

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 = f64::from(self.0);
            fmt::LowerExp::fmt(&val, f) // delegate to f64's implementation
        }
    }

    let l = Length(100);

    assert_eq!(
        format!("l in scientific notation is: {:e}", l),
        "l in scientific notation is: 1e2"
    );

    assert_eq!(
        format!("l in scientific notation is: {:05e}", l),
        "l in scientific notation is: 001e2"
    );

Run

## Required methods

[src]

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

Formats the value using the given formatter.

## Implementors

[src]

### impl LowerExp for f32

[src]

### impl LowerExp for f64

1.42.0[src]

### impl LowerExp for i8

1.42.0[src]

### impl LowerExp for i16

1.42.0[src]

### impl LowerExp for i32

1.42.0[src]

### impl LowerExp for i64

1.42.0[src]

### impl LowerExp for i128

1.42.0[src]

### impl LowerExp for isize

1.42.0[src]

### impl LowerExp for u8

1.42.0[src]

### impl LowerExp for u16

1.42.0[src]

### impl LowerExp for u32

1.42.0[src]

### impl LowerExp for u64

1.42.0[src]

### impl LowerExp for u128

1.42.0[src]

### impl LowerExp for usize

[src]

### impl<'_, T> LowerExp for &'_ T where
T: LowerExp + ?Sized,

[src]

### impl<'_, T> LowerExp for &'_ mut T where
T: LowerExp + ?Sized,