Struct RangeTo 

pub struct RangeTo<Idx> {
    pub end: Idx,
}

A range only bounded exclusively above (..end).

The RangeTo ..end contains all values with x < end. It cannot serve as an Iterator because it doesn’t have a starting point.

Examples

The ..end syntax is a RangeTo:

assert_eq!((..5), std::ops::RangeTo { end: 5 });

It does not have an IntoIterator implementation, so you can’t use it in a for loop directly. This won’t compile:

// error[E0277]: the trait bound `std::ops::RangeTo<{integer}>:
// std::iter::Iterator` is not satisfied
for i in ..5 {
    // ...
}

When used as a slicing index, RangeTo produces a slice of all array elements before the index indicated by end.

let arr = [0, 1, 2, 3, 4];
assert_eq!(arr[ ..  ], [0, 1, 2, 3, 4]);
assert_eq!(arr[ .. 3], [0, 1, 2      ]); // This is a `RangeTo`
assert_eq!(arr[ ..=3], [0, 1, 2, 3   ]);
assert_eq!(arr[1..  ], [   1, 2, 3, 4]);
assert_eq!(arr[1.. 3], [   1, 2      ]);
assert_eq!(arr[1..=3], [   1, 2, 3   ]);

Fields

end: Idx

The upper bound of the range (exclusive).

Trait Implementations

impl<T> IntoBounds<T> for RangeTo<T>

fn into_bounds(self) -> (Bound<T>, Bound<T>)

🔬This is a nightly-only experimental API. (range_into_bounds #136903)

Convert this range into the start and end bounds. Returns (start_bound, end_bound).

impl<T> OneSidedRange<T> for RangeTo<T>

where Self: RangeBounds<T>,

fn bound(self) -> (OneSidedRangeBound, T)

🔬This is a nightly-only experimental API. (one_sided_range #69780)

An internal-only helper function for split_off and split_off_mut that returns the bound of the one-sided range.

impl<T> RangeBounds<T> for RangeTo<&T>

If you need to use this implementation where T is unsized, consider using the RangeBounds impl for a 2-tuple of Bound<&T>, i.e. replace ..end with (Bound::Unbounded, Bound::Excluded(end)).

fn start_bound(&self) -> Bound<&T>

Start index bound.

fn end_bound(&self) -> Bound<&T>

End index bound.

impl<T> RangeBounds<T> for RangeTo<T>

fn start_bound(&self) -> Bound<&T>

Start index bound.

fn end_bound(&self) -> Bound<&T>

End index bound.