pub struct RangeTo<Idx> {
pub end: Idx,
}
Expand description
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).
Implementations§
source§impl<Idx> RangeTo<Idx>where
Idx: PartialOrd,
impl<Idx> RangeTo<Idx>where Idx: PartialOrd,
1.35.0 · sourcepub fn contains<U>(&self, item: &U) -> boolwhere
Idx: PartialOrd<U>,
U: PartialOrd<Idx> + ?Sized,
pub fn contains<U>(&self, item: &U) -> boolwhere Idx: PartialOrd<U>, U: PartialOrd<Idx> + ?Sized,
Returns true
if item
is contained in the range.
Examples
assert!( (..5).contains(&-1_000_000_000));
assert!( (..5).contains(&4));
assert!(!(..5).contains(&5));
assert!( (..1.0).contains(&0.5));
assert!(!(..1.0).contains(&f32::NAN));
assert!(!(..f32::NAN).contains(&0.5));
Trait Implementations§
source§impl<Idx> PartialEq for RangeTo<Idx>where
Idx: PartialEq,
impl<Idx> PartialEq for RangeTo<Idx>where Idx: PartialEq,
1.28.0 · source§impl<T> RangeBounds<T> for RangeTo<&T>
impl<T> RangeBounds<T> for RangeTo<&T>
1.28.0 · source§impl<T> RangeBounds<T> for RangeTo<T>
impl<T> RangeBounds<T> for RangeTo<T>
1.15.0 (const: unstable) · source§impl<T> SliceIndex<[T]> for RangeTo<usize>
impl<T> SliceIndex<[T]> for RangeTo<usize>
const: unstable · source§fn get(self, slice: &[T]) -> Option<&[T]>
fn get(self, slice: &[T]) -> Option<&[T]>
slice_index_methods
)const: unstable · source§fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>
fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>
slice_index_methods
)const: unstable · source§unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]
unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting reference is not used.const: unstable · source§unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]
unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting reference is not used.1.20.0 (const: unstable) · source§impl SliceIndex<str> for RangeTo<usize>
impl SliceIndex<str> for RangeTo<usize>
Implements substring slicing with syntax &self[.. end]
or &mut self[.. end]
.
Returns a slice of the given string from the byte range [0, end
).
Equivalent to &self[0 .. end]
or &mut self[0 .. end]
.
This operation is O(1).
Prior to 1.20.0, these indexing operations were still supported by
direct implementation of Index
and IndexMut
.
Panics
Panics if end
does not point to the starting byte offset of a
character (as defined by is_char_boundary
), or if end > len
.
const: unstable · source§fn get(
self,
slice: &str
) -> Option<&<RangeTo<usize> as SliceIndex<str>>::Output>
fn get( self, slice: &str ) -> Option<&<RangeTo<usize> as SliceIndex<str>>::Output>
slice_index_methods
)const: unstable · source§fn get_mut(
self,
slice: &mut str
) -> Option<&mut <RangeTo<usize> as SliceIndex<str>>::Output>
fn get_mut( self, slice: &mut str ) -> Option<&mut <RangeTo<usize> as SliceIndex<str>>::Output>
slice_index_methods
)const: unstable · source§unsafe fn get_unchecked(
self,
slice: *const str
) -> *const <RangeTo<usize> as SliceIndex<str>>::Output
unsafe fn get_unchecked( self, slice: *const str ) -> *const <RangeTo<usize> as SliceIndex<str>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting reference is not used.const: unstable · source§unsafe fn get_unchecked_mut(
self,
slice: *mut str
) -> *mut <RangeTo<usize> as SliceIndex<str>>::Output
unsafe fn get_unchecked_mut( self, slice: *mut str ) -> *mut <RangeTo<usize> as SliceIndex<str>>::Output
slice_index_methods
)slice
pointer
is undefined behavior even if the resulting reference is not used.