std::ops::Mul - Rust
Description: API documentation for the Rust `Mul` trait in crate `std`.
Keywords: rust, rustlang, rust-lang, Mul

# Trait std::ops::Mul 1.0.0 [−] [src]

    #[lang = "mul"]
    pub trait Mul<RHS = Self> {
        type Output;
        fn mul(self, rhs: RHS) -> Self::Output;
    }

The multiplication operator `*`.

# Examples

Implementing a `Mul`tipliable rational number struct:

    use std::ops::Mul;

    // The uniqueness of rational numbers in lowest terms is a consequence of
    // the fundamental theorem of arithmetic.
    #[derive(Eq)]
    #[derive(PartialEq, Debug)]
    struct Rational {
        nominator: usize,
        denominator: usize,
    }

    impl Rational {
        fn new(nominator: usize, denominator: usize) -> Self {
            if denominator == 0 {
                panic!("Zero is an invalid denominator!");
            }

            // Reduce to lowest terms by dividing by the greatest common
            // divisor.
            let gcd = gcd(nominator, denominator);
            Rational {
                nominator: nominator / gcd,
                denominator: denominator / gcd,
            }
        }
    }

    impl Mul for Rational {
        // The multiplication of rational numbers is a closed operation.
        type Output = Self;

        fn mul(self, rhs: Self) -> Self {
            let nominator = self.nominator * rhs.nominator;
            let denominator = self.denominator * rhs.denominator;
            Rational::new(nominator, denominator)
        }
    }

    // Euclid's two-thousand-year-old algorithm for finding the greatest common
    // divisor.
    fn gcd(x: usize, y: usize) -> usize {
        let mut x = x;
        let mut y = y;
        while y != 0 {
            let t = y;
            y = x % y;
            x = t;
        }
        x
    }

    assert_eq!(Rational::new(1, 2), Rational::new(2, 4));
    assert_eq!(Rational::new(2, 3) * Rational::new(3, 4),
               Rational::new(1, 2));Run

Note that `RHS = Self` by default, but this is not mandatory. Here is an implementation which enables multiplication of vectors by scalars, as is done in linear algebra.

    use std::ops::Mul;

    struct Scalar {value: usize};

    #[derive(Debug)]
    struct Vector {value: Vec<usize>};

    impl Mul<Vector> for Scalar {
        type Output = Vector;

        fn mul(self, rhs: Vector) -> Vector {
            Vector {value: rhs.value.iter().map(|v| self.value * v).collect()}
        }
    }

    impl PartialEq<Vector> for Vector {
        fn eq(&self, other: &Self) -> bool {
            self.value == other.value
        }
    }

    let scalar = Scalar{value: 3};
    let vector = Vector{value: vec![2, 4, 6]};
    assert_eq!(scalar * vector, Vector{value: vec![6, 12, 18]});Run

## Associated Types

### `type Output`

The resulting type after applying the `*` operator

## Required Methods

### `fn mul(self, rhs: RHS) -> Self::Output`

The method for the `*` operator

## Implementors

- `impl<'a> Mul<i32> for &'a i32`
- `impl Mul<i32> for i32`
- `impl<'a> Mul<Wrapping<isize>> for &'a Wrapping<isize>`
- `impl Mul<i16> for i16`
- `impl<'a> Mul<&'a i32> for i32`
- `impl<'a> Mul<&'a Wrapping<usize>> for Wrapping<usize>`
- `impl<'a> Mul<&'a Wrapping<isize>> for Wrapping<isize>`
- `impl<'a, 'b> Mul<&'a Wrapping<u128>> for &'b Wrapping<u128>`
- `impl<'a, 'b> Mul<&'a i16> for &'b i16`
- `impl Mul<u32> for u32`
- `impl Mul<u64> for u64`
- `impl<'a, 'b> Mul<&'a Wrapping<u16>> for &'b Wrapping<u16>`
- `impl<'a> Mul<u64> for &'a u64`
- `impl Mul<Wrapping<i128>> for Wrapping<i128>`
- `impl Mul<f64> for f64`
- `impl<'a> Mul<&'a i8> for i8`
- `impl Mul<Wrapping<usize>> for Wrapping<usize>`
- `impl Mul<Wrapping<u16>> for Wrapping<u16>`
- `impl<'a, 'b> Mul<&'a u8> for &'b u8`
- `impl Mul<isize> for isize`
- `impl<'a, 'b> Mul<&'a Wrapping<u8>> for &'b Wrapping<u8>`
- `impl<'a> Mul<Wrapping<i32>> for &'a Wrapping<i32>`
- `impl Mul<u16> for u16`
- `impl<'a, 'b> Mul<&'a isize> for &'b isize`
- `impl<'a> Mul<u32> for &'a u32`
- `impl<'a> Mul<&'a Wrapping<u64>> for Wrapping<u64>`
- `impl<'a> Mul<u16> for &'a u16`
- `impl Mul<f32> for f32`
- `impl<'a> Mul<&'a u128> for u128`
- `impl<'a, 'b> Mul<&'a u64> for &'b u64`
- `impl<'a> Mul<u128> for &'a u128`
- `impl<'a> Mul<&'a i16> for i16`
- `impl<'a, 'b> Mul<&'a f32> for &'b f32`
- `impl<'a> Mul<Wrapping<u32>> for &'a Wrapping<u32>`
- `impl<'a, 'b> Mul<&'a Wrapping<i8>> for &'b Wrapping<i8>`
- `impl<'a, 'b> Mul<&'a i8> for &'b i8`
- `impl Mul<Wrapping<i32>> for Wrapping<i32>`
- `impl<'a, 'b> Mul<&'a u16> for &'b u16`
- `impl Mul<Wrapping<i16>> for Wrapping<i16>`
- `impl<'a, 'b> Mul<&'a usize> for &'b usize`
- `impl<'a> Mul<u8> for &'a u8`
- `impl Mul<Wrapping<u32>> for Wrapping<u32>`
- `impl<'a> Mul<&'a Wrapping<u128>> for Wrapping<u128>`
- `impl<'a, 'b> Mul<&'a f64> for &'b f64`
- `impl<'a> Mul<&'a usize> for usize`
- `impl<'a> Mul<Wrapping<u8>> for &'a Wrapping<u8>`
- `impl<'a, 'b> Mul<&'a Wrapping<usize>> for &'b Wrapping<usize>`
- `impl<'a, 'b> Mul<&'a i64> for &'b i64`
- `impl<'a> Mul<Wrapping<u64>> for &'a Wrapping<u64>`
- `impl<'a> Mul<Wrapping<u128>> for &'a Wrapping<u128>`
- `impl<'a> Mul<Wrapping<u16>> for &'a Wrapping<u16>`
- `impl<'a> Mul<Wrapping<i8>> for &'a Wrapping<i8>`
- `impl<'a> Mul<i8> for &'a i8`
- `impl<'a> Mul<&'a Wrapping<i32>> for Wrapping<i32>`
- `impl Mul<u128> for u128`
- `impl<'a, 'b> Mul<&'a u128> for &'b u128`
- `impl<'a> Mul<&'a isize> for isize`
- `impl Mul<i128> for i128`
- `impl Mul<u8> for u8`
- `impl<'a, 'b> Mul<&'a Wrapping<u32>> for &'b Wrapping<u32>`
- `impl<'a> Mul<isize> for &'a isize`
- `impl<'a> Mul<usize> for &'a usize`
- `impl Mul<Wrapping<i64>> for Wrapping<i64>`
- `impl<'a> Mul<&'a i128> for i128`
- `impl<'a> Mul<&'a Wrapping<i8>> for Wrapping<i8>`
- `impl<'a> Mul<i128> for &'a i128`
- `impl<'a> Mul<i16> for &'a i16`
- `impl Mul<Wrapping<u64>> for Wrapping<u64>`
- `impl<'a, 'b> Mul<&'a Wrapping<isize>> for &'b Wrapping<isize>`
- `impl Mul<i8> for i8`
- `impl<'a, 'b> Mul<&'a Wrapping<u64>> for &'b Wrapping<u64>`
- `impl<'a> Mul<Wrapping<i16>> for &'a Wrapping<i16>`
- `impl<'a> Mul<&'a f64> for f64`
- `impl Mul<i64> for i64`
- `impl<'a> Mul<Wrapping<i64>> for &'a Wrapping<i64>`
- `impl<'a> Mul<f32> for &'a f32`
- `impl<'a> Mul<&'a u16> for u16`
- `impl<'a, 'b> Mul<&'a i32> for &'b i32`
- `impl<'a> Mul<f64> for &'a f64`
- `impl<'a> Mul<Wrapping<i128>> for &'a Wrapping<i128>`
- `impl<'a> Mul<&'a Wrapping<u32>> for Wrapping<u32>`
- `impl<'a, 'b> Mul<&'a u32> for &'b u32`
- `impl<'a> Mul<&'a Wrapping<i64>> for Wrapping<i64>`
- `impl<'a> Mul<&'a u8> for u8`
- `impl Mul<Wrapping<u128>> for Wrapping<u128>`
- `impl Mul<Wrapping<u8>> for Wrapping<u8>`
- `impl<'a> Mul<&'a i64> for i64`
- `impl<'a> Mul<&'a Wrapping<i128>> for Wrapping<i128>`
- `impl<'a, 'b> Mul<&'a Wrapping<i128>> for &'b Wrapping<i128>`
- `impl<'a> Mul<&'a u64> for u64`
- `impl Mul<Wrapping<isize>> for Wrapping<isize>`
- `impl<'a, 'b> Mul<&'a i128> for &'b i128`
- `impl<'a> Mul<&'a u32> for u32`
- `impl Mul<usize> for usize`
- `impl<'a> Mul<&'a Wrapping<i16>> for Wrapping<i16>`
- `impl<'a> Mul<&'a Wrapping<u16>> for Wrapping<u16>`
- `impl<'a, 'b> Mul<&'a Wrapping<i64>> for &'b Wrapping<i64>`
- `impl<'a> Mul<&'a Wrapping<u8>> for Wrapping<u8>`
- `impl<'a> Mul<&'a f32> for f32`
- `impl<'a> Mul<Wrapping<usize>> for &'a Wrapping<usize>`
- `impl<'a> Mul<i64> for &'a i64`
- `impl<'a, 'b> Mul<&'a Wrapping<i32>> for &'b Wrapping<i32>`
- `impl Mul<Wrapping<i8>> for Wrapping<i8>`
- `impl<'a, 'b> Mul<&'a Wrapping<i16>> for &'b Wrapping<i16>`
- `impl Mul<u32> for Duration`

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