Trait core::cmp::PartialOrd [−] [src]

```pub trait PartialOrd<Rhs: ?Sized = Self>: PartialEq<Rhs> {
fn partial_cmp(&self, other: &Rhs) -> Option<Ordering>;

fn lt(&self, other: &Rhs) -> bool { ... }
fn le(&self, other: &Rhs) -> bool { ... }
fn gt(&self, other: &Rhs) -> bool { ... }
fn ge(&self, other: &Rhs) -> bool { ... }
}```

Trait for values that can be compared for a sort-order.

The comparison must satisfy, for all `a`, `b` and `c`:

• antisymmetry: if `a < b` then `!(a > b)` and vice versa; and
• transitivity: `a < b` and `b < c` implies `a < c`. The same must hold for both `==` and `>`.

Note that these requirements mean that the trait itself must be implemented symmetrically and transitively: if `T: PartialOrd<U>` and `U: PartialOrd<V>` then `U: PartialOrd<T>` and `T: PartialOrd<V>`.

PartialOrd only requires implementation of the `partial_cmp` method, with the others generated from default implementations.

However it remains possible to implement the others separately for types which do not have a total order. For example, for floating point numbers, `NaN < 0 == false` and `NaN >= 0 == false` (cf. IEEE 754-2008 section 5.11).

Required Methods

`fn partial_cmp(&self, other: &Rhs) -> Option<Ordering>`

This method returns an ordering between `self` and `other` values if one exists.

Examples

fn main() { use std::cmp::Ordering; let result = 1.0.partial_cmp(&2.0); assert_eq!(result, Some(Ordering::Less)); let result = 1.0.partial_cmp(&1.0); assert_eq!(result, Some(Ordering::Equal)); let result = 2.0.partial_cmp(&1.0); assert_eq!(result, Some(Ordering::Greater)); }
```use std::cmp::Ordering;

let result = 1.0.partial_cmp(&2.0);
assert_eq!(result, Some(Ordering::Less));

let result = 1.0.partial_cmp(&1.0);
assert_eq!(result, Some(Ordering::Equal));

let result = 2.0.partial_cmp(&1.0);
assert_eq!(result, Some(Ordering::Greater));```

When comparison is impossible:

fn main() { let result = std::f64::NAN.partial_cmp(&1.0); assert_eq!(result, None); }
```let result = std::f64::NAN.partial_cmp(&1.0);
assert_eq!(result, None);```

Provided Methods

`fn lt(&self, other: &Rhs) -> bool`

This method tests less than (for `self` and `other`) and is used by the `<` operator.

Examples

fn main() { use std::cmp::Ordering; let result = 1.0 < 2.0; assert_eq!(result, true); let result = 2.0 < 1.0; assert_eq!(result, false); }
```use std::cmp::Ordering;

let result = 1.0 < 2.0;
assert_eq!(result, true);

let result = 2.0 < 1.0;
assert_eq!(result, false);```

`fn le(&self, other: &Rhs) -> bool`

This method tests less than or equal to (for `self` and `other`) and is used by the `<=` operator.

Examples

fn main() { let result = 1.0 <= 2.0; assert_eq!(result, true); let result = 2.0 <= 2.0; assert_eq!(result, true); }
```let result = 1.0 <= 2.0;
assert_eq!(result, true);

let result = 2.0 <= 2.0;
assert_eq!(result, true);```

`fn gt(&self, other: &Rhs) -> bool`

This method tests greater than (for `self` and `other`) and is used by the `>` operator.

Examples

fn main() { let result = 1.0 > 2.0; assert_eq!(result, false); let result = 2.0 > 2.0; assert_eq!(result, false); }
```let result = 1.0 > 2.0;
assert_eq!(result, false);

let result = 2.0 > 2.0;
assert_eq!(result, false);```

`fn ge(&self, other: &Rhs) -> bool`

This method tests greater than or equal to (for `self` and `other`) and is used by the `>=` operator.

Examples

fn main() { let result = 2.0 >= 1.0; assert_eq!(result, true); let result = 2.0 >= 2.0; assert_eq!(result, true); }
```let result = 2.0 >= 1.0;
assert_eq!(result, true);

let result = 2.0 >= 2.0;
assert_eq!(result, true);```

Implementors

• `impl<T: PartialOrd> PartialOrd for Wrapping<T>`
• `impl<T: PartialOrd + Zeroable> PartialOrd for NonZero<T>`
• `impl<T: ?Sized> PartialOrd for *const T`
• `impl<T: ?Sized> PartialOrd for *mut T`
• `impl PartialOrd for NoCopy`
• `impl<T: ?Sized> PartialOrd for PhantomData<T>`
• `impl PartialOrd for ()`
• `impl PartialOrd for bool`
• `impl PartialOrd for char`
• `impl PartialOrd for usize`
• `impl PartialOrd for u8`
• `impl PartialOrd for u16`
• `impl PartialOrd for u32`
• `impl PartialOrd for u64`
• `impl PartialOrd for isize`
• `impl PartialOrd for i8`
• `impl PartialOrd for i16`
• `impl PartialOrd for i32`
• `impl PartialOrd for i64`
• `impl PartialOrd for f32`
• `impl PartialOrd for f64`
• `impl<'a, 'b, A: ?Sized, B: ?Sized> PartialOrd<&'b B> for &'a A where A: PartialOrd<B>`
• `impl<'a, 'b, A: ?Sized, B: ?Sized> PartialOrd<&'b mut B> for &'a mut A where A: PartialOrd<B>`
• `impl PartialOrd for Ordering`
• `impl<T: PartialOrd> PartialOrd for [T; 0]`
• `impl<T: PartialOrd> PartialOrd for [T; 1]`
• `impl<T: PartialOrd> PartialOrd for [T; 2]`
• `impl<T: PartialOrd> PartialOrd for [T; 3]`
• `impl<T: PartialOrd> PartialOrd for [T; 4]`
• `impl<T: PartialOrd> PartialOrd for [T; 5]`
• `impl<T: PartialOrd> PartialOrd for [T; 6]`
• `impl<T: PartialOrd> PartialOrd for [T; 7]`
• `impl<T: PartialOrd> PartialOrd for [T; 8]`
• `impl<T: PartialOrd> PartialOrd for [T; 9]`
• `impl<T: PartialOrd> PartialOrd for [T; 10]`
• `impl<T: PartialOrd> PartialOrd for [T; 11]`
• `impl<T: PartialOrd> PartialOrd for [T; 12]`
• `impl<T: PartialOrd> PartialOrd for [T; 13]`
• `impl<T: PartialOrd> PartialOrd for [T; 14]`
• `impl<T: PartialOrd> PartialOrd for [T; 15]`
• `impl<T: PartialOrd> PartialOrd for [T; 16]`
• `impl<T: PartialOrd> PartialOrd for [T; 17]`
• `impl<T: PartialOrd> PartialOrd for [T; 18]`
• `impl<T: PartialOrd> PartialOrd for [T; 19]`
• `impl<T: PartialOrd> PartialOrd for [T; 20]`
• `impl<T: PartialOrd> PartialOrd for [T; 21]`
• `impl<T: PartialOrd> PartialOrd for [T; 22]`
• `impl<T: PartialOrd> PartialOrd for [T; 23]`
• `impl<T: PartialOrd> PartialOrd for [T; 24]`
• `impl<T: PartialOrd> PartialOrd for [T; 25]`
• `impl<T: PartialOrd> PartialOrd for [T; 26]`
• `impl<T: PartialOrd> PartialOrd for [T; 27]`
• `impl<T: PartialOrd> PartialOrd for [T; 28]`
• `impl<T: PartialOrd> PartialOrd for [T; 29]`
• `impl<T: PartialOrd> PartialOrd for [T; 30]`
• `impl<T: PartialOrd> PartialOrd for [T; 31]`
• `impl<T: PartialOrd> PartialOrd for [T; 32]`
• `impl<T: PartialOrd> PartialOrd for Option<T>`
• `impl<T: PartialOrd, E: PartialOrd> PartialOrd for Result<T, E>`
• `impl<T: PartialOrd> PartialOrd for [T]`
• `impl PartialOrd for str`
• `impl<A: PartialOrd + PartialEq> PartialOrd for (A,)`
• `impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq> PartialOrd for (A, B)`
• `impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq, C: PartialOrd + PartialEq> PartialOrd for (A, B, C)`
• `impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq, C: PartialOrd + PartialEq, D: PartialOrd + PartialEq> PartialOrd for (A, B, C, D)`
• `impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq, C: PartialOrd + PartialEq, D: PartialOrd + PartialEq, E: PartialOrd + PartialEq> PartialOrd for (A, B, C, D, E)`
• `impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq, C: PartialOrd + PartialEq, D: PartialOrd + PartialEq, E: PartialOrd + PartialEq, F: PartialOrd + PartialEq> PartialOrd for (A, B, C, D, E, F)`
• `impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq, C: PartialOrd + PartialEq, D: PartialOrd + PartialEq, E: PartialOrd + PartialEq, F: PartialOrd + PartialEq, G: PartialOrd + PartialEq> PartialOrd for (A, B, C, D, E, F, G)`
• `impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq, C: PartialOrd + PartialEq, D: PartialOrd + PartialEq, E: PartialOrd + PartialEq, F: PartialOrd + PartialEq, G: PartialOrd + PartialEq, H: PartialOrd + PartialEq> PartialOrd for (A, B, C, D, E, F, G, H)`
• `impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq, C: PartialOrd + PartialEq, D: PartialOrd + PartialEq, E: PartialOrd + PartialEq, F: PartialOrd + PartialEq, G: PartialOrd + PartialEq, H: PartialOrd + PartialEq, I: PartialOrd + PartialEq> PartialOrd for (A, B, C, D, E, F, G, H, I)`
• `impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq, C: PartialOrd + PartialEq, D: PartialOrd + PartialEq, E: PartialOrd + PartialEq, F: PartialOrd + PartialEq, G: PartialOrd + PartialEq, H: PartialOrd + PartialEq, I: PartialOrd + PartialEq, J: PartialOrd + PartialEq> PartialOrd for (A, B, C, D, E, F, G, H, I, J)`
• `impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq, C: PartialOrd + PartialEq, D: PartialOrd + PartialEq, E: PartialOrd + PartialEq, F: PartialOrd + PartialEq, G: PartialOrd + PartialEq, H: PartialOrd + PartialEq, I: PartialOrd + PartialEq, J: PartialOrd + PartialEq, K: PartialOrd + PartialEq> PartialOrd for (A, B, C, D, E, F, G, H, I, J, K)`
• `impl<A: PartialOrd + PartialEq, B: PartialOrd + PartialEq, C: PartialOrd + PartialEq, D: PartialOrd + PartialEq, E: PartialOrd + PartialEq, F: PartialOrd + PartialEq, G: PartialOrd + PartialEq, H: PartialOrd + PartialEq, I: PartialOrd + PartialEq, J: PartialOrd + PartialEq, K: PartialOrd + PartialEq, L: PartialOrd + PartialEq> PartialOrd for (A, B, C, D, E, F, G, H, I, J, K, L)`