# Trait alloc::fmt::UpperExp

1.0.0 · 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");

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 = 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"
    );

Run

## Required Methods§

source

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

Formats the value using the given formatter.

## Implementors§

source§

### impl UpperExp for f32

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

source§

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

source§

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