Struct std::ops::RangeFrom

pub struct RangeFrom<Idx> {
    pub start: Idx,
}

A range only bounded inclusively below (start..).

The RangeFrom start.. contains all values with x >= start.

Note: Overflow in the Iterator implementation (when the contained data type reaches its numerical limit) is allowed to panic, wrap, or saturate. This behavior is defined by the implementation of the Step trait. For primitive integers, this follows the normal rules, and respects the overflow checks profile (panic in debug, wrap in release). Note also that overflow happens earlier than you might assume: the overflow happens in the call to next that yields the maximum value, as the range must be set to a state to yield the next value.

Examples

The start.. syntax is a RangeFrom:

assert_eq!((2..), std::ops::RangeFrom { start: 2 });
assert_eq!(2 + 3 + 4, (2..).take(3).sum());

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

Fields

start: Idx

The lower bound of the range (inclusive).

Implementations

impl<Idx> RangeFrom<Idx>where
    Idx: PartialOrd<Idx>,

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!(!(3..).contains(&2));
assert!( (3..).contains(&3));
assert!( (3..).contains(&1_000_000_000));

assert!( (0.0..).contains(&0.5));
assert!(!(0.0..).contains(&f32::NAN));
assert!(!(f32::NAN..).contains(&0.5));

Trait Implementations

impl<Idx> Clone for RangeFrom<Idx>where
    Idx: Clone,

fn clone(&self) -> RangeFrom<Idx>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<Idx> Debug for RangeFrom<Idx>where
    Idx: Debug,

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

Formats the value using the given formatter.

impl<Idx> Hash for RangeFrom<Idx>where
    Idx: Hash,

fn hash<__H>(&self, state: &mut __H)where
    __H: Hasher,

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)where
    H: Hasher,
    Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Index<RangeFrom<usize>> for CStr

type Output = CStr

The returned type after indexing.

fn index(&self, index: RangeFrom<usize>) -> &CStr

Performs the indexing (container[index]) operation.

impl Index<RangeFrom<usize>> for String

type Output = str

The returned type after indexing.

fn index(&self, index: RangeFrom<usize>) -> &str

Performs the indexing (container[index]) operation.

impl IndexMut<RangeFrom<usize>> for String

fn index_mut(&mut self, index: RangeFrom<usize>) -> &mut str

Performs the mutable indexing (container[index]) operation.

impl<A> Iterator for RangeFrom<A>where
    A: Step,

type Item = A

The type of the elements being iterated over.

fn next(&mut self) -> Option<A>

Advances the iterator and returns the next value.

fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the iterator.

fn nth(&mut self, n: usize) -> Option<A>

Returns the nth element of the iterator.

fn next_chunk<const N: usize>(
    &mut self
) -> Result<[Self::Item; N], IntoIter<Self::Item, N>>where
    Self: Sized,

🔬This is a nightly-only experimental API. (iter_next_chunk #98326)

Advances the iterator and returns an array containing the next N values.

fn count(self) -> usizewhere
    Self: Sized,

Consumes the iterator, counting the number of iterations and returning it.

fn last(self) -> Option<Self::Item>where
    Self: Sized,

Consumes the iterator, returning the last element.

fn advance_by(&mut self, n: usize) -> Result<(), usize>

🔬This is a nightly-only experimental API. (iter_advance_by #77404)

Advances the iterator by n elements.

fn step_by(self, step: usize) -> StepBy<Self> where
    Self: Sized,

Creates an iterator starting at the same point, but stepping by the given amount at each iteration.

fn chain<U>(self, other: U) -> Chain<Self, <U as IntoIterator>::IntoIter> where
    Self: Sized,
    U: IntoIterator<Item = Self::Item>,

Takes two iterators and creates a new iterator over both in sequence.

fn zip<U>(self, other: U) -> Zip<Self, <U as IntoIterator>::IntoIter> where
    Self: Sized,
    U: IntoIterator,

‘Zips up’ two iterators into a single iterator of pairs.

fn intersperse_with<G>(self, separator: G) -> IntersperseWith<Self, G> where
    Self: Sized,
    G: FnMut() -> Self::Item,

🔬This is a nightly-only experimental API. (iter_intersperse #79524)

Creates a new iterator which places an item generated by separator between adjacent items of the original iterator.

fn map<B, F>(self, f: F) -> Map<Self, F> where
    Self: Sized,
    F: FnMut(Self::Item) -> B,

Takes a closure and creates an iterator which calls that closure on each element.

fn for_each<F>(self, f: F)where
    Self: Sized,
    F: FnMut(Self::Item),

Calls a closure on each element of an iterator.

fn filter<P>(self, predicate: P) -> Filter<Self, P> where
    Self: Sized,
    P: FnMut(&Self::Item) -> bool,

Creates an iterator which uses a closure to determine if an element should be yielded.

fn filter_map<B, F>(self, f: F) -> FilterMap<Self, F> where
    Self: Sized,
    F: FnMut(Self::Item) -> Option<B>,

Creates an iterator that both filters and maps.

fn enumerate(self) -> Enumerate<Self> where
    Self: Sized,

Creates an iterator which gives the current iteration count as well as the next value.

fn peekable(self) -> Peekable<Self> where
    Self: Sized,

Creates an iterator which can use the peek and peek_mut methods to look at the next element of the iterator without consuming it. See their documentation for more information.

fn skip_while<P>(self, predicate: P) -> SkipWhile<Self, P> where
    Self: Sized,
    P: FnMut(&Self::Item) -> bool,

Creates an iterator that skips elements based on a predicate.

fn take_while<P>(self, predicate: P) -> TakeWhile<Self, P> where
    Self: Sized,
    P: FnMut(&Self::Item) -> bool,

Creates an iterator that yields elements based on a predicate.

fn map_while<B, P>(self, predicate: P) -> MapWhile<Self, P> where
    Self: Sized,
    P: FnMut(Self::Item) -> Option<B>,

Creates an iterator that both yields elements based on a predicate and maps.

fn skip(self, n: usize) -> Skip<Self> where
    Self: Sized,

Creates an iterator that skips the first n elements.

fn take(self, n: usize) -> Take<Self> where
    Self: Sized,

Creates an iterator that yields the first n elements, or fewer if the underlying iterator ends sooner.

fn scan<St, B, F>(self, initial_state: St, f: F) -> Scan<Self, St, F> where
    Self: Sized,
    F: FnMut(&mut St, Self::Item) -> Option<B>,

An iterator adapter similar to fold that holds internal state and produces a new iterator.

fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F> where
    Self: Sized,
    U: IntoIterator,
    F: FnMut(Self::Item) -> U,

Creates an iterator that works like map, but flattens nested structure.

fn fuse(self) -> Fuse<Self> where
    Self: Sized,

Creates an iterator which ends after the first None.

fn inspect<F>(self, f: F) -> Inspect<Self, F> where
    Self: Sized,
    F: FnMut(&Self::Item),

Does something with each element of an iterator, passing the value on.

fn by_ref(&mut self) -> &mut Selfwhere
    Self: Sized,

Borrows an iterator, rather than consuming it.

fn collect<B>(self) -> Bwhere
    B: FromIterator<Self::Item>,
    Self: Sized,

Transforms an iterator into a collection.

fn collect_into<E>(self, collection: &mut E) -> &mut Ewhere
    E: Extend<Self::Item>,
    Self: Sized,

🔬This is a nightly-only experimental API. (iter_collect_into #94780)

Collects all the items from an iterator into a collection.

fn partition<B, F>(self, f: F) -> (B, B)where
    Self: Sized,
    B: Default + Extend<Self::Item>,
    F: FnMut(&Self::Item) -> bool,

Consumes an iterator, creating two collections from it.

fn is_partitioned<P>(self, predicate: P) -> boolwhere
    Self: Sized,
    P: FnMut(Self::Item) -> bool,

🔬This is a nightly-only experimental API. (iter_is_partitioned #62544)

Checks if the elements of this iterator are partitioned according to the given predicate, such that all those that return true precede all those that return false.

fn try_fold<B, F, R>(&mut self, init: B, f: F) -> Rwhere
    Self: Sized,
    F: FnMut(B, Self::Item) -> R,
    R: Try<Output = B>,

An iterator method that applies a function as long as it returns successfully, producing a single, final value.

fn try_for_each<F, R>(&mut self, f: F) -> Rwhere
    Self: Sized,
    F: FnMut(Self::Item) -> R,
    R: Try<Output = ()>,

An iterator method that applies a fallible function to each item in the iterator, stopping at the first error and returning that error.

fn fold<B, F>(self, init: B, f: F) -> Bwhere
    Self: Sized,
    F: FnMut(B, Self::Item) -> B,

Folds every element into an accumulator by applying an operation, returning the final result.

fn reduce<F>(self, f: F) -> Option<Self::Item>where
    Self: Sized,
    F: FnMut(Self::Item, Self::Item) -> Self::Item,

Reduces the elements to a single one, by repeatedly applying a reducing operation.

fn try_reduce<F, R>(
    &mut self,
    f: F
) -> <<R as Try>::Residual as Residual<Option<<R as Try>::Output>>>::TryTypewhere
    Self: Sized,
    F: FnMut(Self::Item, Self::Item) -> R,
    R: Try<Output = Self::Item>,
    <R as Try>::Residual: Residual<Option<Self::Item>>,

🔬This is a nightly-only experimental API. (iterator_try_reduce #87053)

Reduces the elements to a single one by repeatedly applying a reducing operation. If the closure returns a failure, the failure is propagated back to the caller immediately.

fn all<F>(&mut self, f: F) -> boolwhere
    Self: Sized,
    F: FnMut(Self::Item) -> bool,

Tests if every element of the iterator matches a predicate.

fn any<F>(&mut self, f: F) -> boolwhere
    Self: Sized,
    F: FnMut(Self::Item) -> bool,

Tests if any element of the iterator matches a predicate.

fn find<P>(&mut self, predicate: P) -> Option<Self::Item>where
    Self: Sized,
    P: FnMut(&Self::Item) -> bool,

Searches for an element of an iterator that satisfies a predicate.

fn find_map<B, F>(&mut self, f: F) -> Option<B>where
    Self: Sized,
    F: FnMut(Self::Item) -> Option<B>,

Applies function to the elements of iterator and returns the first non-none result.

fn try_find<F, R>(
    &mut self,
    f: F
) -> <<R as Try>::Residual as Residual<Option<Self::Item>>>::TryTypewhere
    Self: Sized,
    F: FnMut(&Self::Item) -> R,
    R: Try<Output = bool>,
    <R as Try>::Residual: Residual<Option<Self::Item>>,

🔬This is a nightly-only experimental API. (try_find #63178)

Applies function to the elements of iterator and returns the first true result or the first error.

fn position<P>(&mut self, predicate: P) -> Option<usize>where
    Self: Sized,
    P: FnMut(Self::Item) -> bool,

Searches for an element in an iterator, returning its index.

fn max_by_key<B, F>(self, f: F) -> Option<Self::Item>where
    B: Ord,
    Self: Sized,
    F: FnMut(&Self::Item) -> B,

Returns the element that gives the maximum value from the specified function.

fn max_by<F>(self, compare: F) -> Option<Self::Item>where
    Self: Sized,
    F: FnMut(&Self::Item, &Self::Item) -> Ordering,

Returns the element that gives the maximum value with respect to the specified comparison function.

fn min_by_key<B, F>(self, f: F) -> Option<Self::Item>where
    B: Ord,
    Self: Sized,
    F: FnMut(&Self::Item) -> B,

Returns the element that gives the minimum value from the specified function.

fn min_by<F>(self, compare: F) -> Option<Self::Item>where
    Self: Sized,
    F: FnMut(&Self::Item, &Self::Item) -> Ordering,

Returns the element that gives the minimum value with respect to the specified comparison function.

fn unzip<A, B, FromA, FromB>(self) -> (FromA, FromB)where
    FromA: Default + Extend<A>,
    FromB: Default + Extend<B>,
    Self: Sized + Iterator<Item = (A, B)>,

Converts an iterator of pairs into a pair of containers.

fn copied<'a, T>(self) -> Copied<Self> where
    T: 'a + Copy,
    Self: Sized + Iterator<Item = &'a T>,

Creates an iterator which copies all of its elements.

fn cloned<'a, T>(self) -> Cloned<Self> where
    T: 'a + Clone,
    Self: Sized + Iterator<Item = &'a T>,

Creates an iterator which clones all of its elements.

fn cycle(self) -> Cycle<Self> where
    Self: Sized + Clone,

Repeats an iterator endlessly.

fn array_chunks<const N: usize>(self) -> ArrayChunks<Self, N> where
    Self: Sized,

🔬This is a nightly-only experimental API. (iter_array_chunks #100450)

Returns an iterator over N elements of the iterator at a time.

fn sum<S>(self) -> Swhere
    Self: Sized,
    S: Sum<Self::Item>,

Sums the elements of an iterator.

fn product<P>(self) -> Pwhere
    Self: Sized,
    P: Product<Self::Item>,

Iterates over the entire iterator, multiplying all the elements

fn cmp_by<I, F>(self, other: I, cmp: F) -> Orderingwhere
    Self: Sized,
    I: IntoIterator,
    F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Ordering,

🔬This is a nightly-only experimental API. (iter_order_by #64295)

Lexicographically compares the elements of this Iterator with those of another with respect to the specified comparison function.

fn partial_cmp<I>(self, other: I) -> Option<Ordering>where
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>,
    Self: Sized,

Lexicographically compares the elements of this Iterator with those of another.

fn partial_cmp_by<I, F>(self, other: I, partial_cmp: F) -> Option<Ordering>where
    Self: Sized,
    I: IntoIterator,
    F: FnMut(Self::Item, <I as IntoIterator>::Item) -> Option<Ordering>,

🔬This is a nightly-only experimental API. (iter_order_by #64295)

Lexicographically compares the elements of this Iterator with those of another with respect to the specified comparison function.

fn eq<I>(self, other: I) -> boolwhere
    I: IntoIterator,
    Self::Item: PartialEq<<I as IntoIterator>::Item>,
    Self: Sized,

Determines if the elements of this Iterator are equal to those of another.

fn eq_by<I, F>(self, other: I, eq: F) -> boolwhere
    Self: Sized,
    I: IntoIterator,
    F: FnMut(Self::Item, <I as IntoIterator>::Item) -> bool,

🔬This is a nightly-only experimental API. (iter_order_by #64295)

Determines if the elements of this Iterator are equal to those of another with respect to the specified equality function.

fn ne<I>(self, other: I) -> boolwhere
    I: IntoIterator,
    Self::Item: PartialEq<<I as IntoIterator>::Item>,
    Self: Sized,

Determines if the elements of this Iterator are unequal to those of another.

fn lt<I>(self, other: I) -> boolwhere
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>,
    Self: Sized,

Determines if the elements of this Iterator are lexicographically less than those of another.

fn le<I>(self, other: I) -> boolwhere
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>,
    Self: Sized,

Determines if the elements of this Iterator are lexicographically less or equal to those of another.

fn gt<I>(self, other: I) -> boolwhere
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>,
    Self: Sized,

Determines if the elements of this Iterator are lexicographically greater than those of another.

fn ge<I>(self, other: I) -> boolwhere
    I: IntoIterator,
    Self::Item: PartialOrd<<I as IntoIterator>::Item>,
    Self: Sized,

Determines if the elements of this Iterator are lexicographically greater than or equal to those of another.

fn is_sorted_by<F>(self, compare: F) -> boolwhere
    Self: Sized,
    F: FnMut(&Self::Item, &Self::Item) -> Option<Ordering>,

🔬This is a nightly-only experimental API. (is_sorted #53485)

Checks if the elements of this iterator are sorted using the given comparator function.

fn is_sorted_by_key<F, K>(self, f: F) -> boolwhere
    Self: Sized,
    F: FnMut(Self::Item) -> K,
    K: PartialOrd<K>,

🔬This is a nightly-only experimental API. (is_sorted #53485)

Checks if the elements of this iterator are sorted using the given key extraction function.

impl<Idx> PartialEq<RangeFrom<Idx>> for RangeFrom<Idx>where
    Idx: PartialEq<Idx>,

fn eq(&self, other: &RangeFrom<Idx>) -> bool

This method tests for self and other values to be equal, and is used by ==.

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

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<T> RangeBounds<T> for RangeFrom<&T>

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

Start index bound.

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

End index bound.

fn contains<U>(&self, item: &U) -> boolwhere
    T: PartialOrd<U>,
    U: PartialOrd<T> + ?Sized,

Returns true if item is contained in the range.

impl<T> RangeBounds<T> for RangeFrom<T>

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

Start index bound.

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

End index bound.

fn contains<U>(&self, item: &U) -> boolwhere
    T: PartialOrd<U>,
    U: PartialOrd<T> + ?Sized,

Returns true if item is contained in the range.

impl<T> SliceIndex<[T]> for RangeFrom<usize>

type Output = [T]

The output type returned by methods.

fn get(self, slice: &[T]) -> Option<&[T]>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, if in bounds.

fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, if in bounds.

unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, without performing any bounds checking. Calling this method with an out-of-bounds index or a dangling slice pointer is undefined behavior even if the resulting reference is not used.

unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, without performing any bounds checking. Calling this method with an out-of-bounds index or a dangling slice pointer is undefined behavior even if the resulting reference is not used.

fn index(self, slice: &[T]) -> &[T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, panicking if out of bounds.

fn index_mut(self, slice: &mut [T]) -> &mut [T]

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, panicking if out of bounds.

impl SliceIndex<str> for RangeFrom<usize>

Implements substring slicing with syntax &self[begin ..] or &mut self[begin ..].

Returns a slice of the given string from the byte range [begin, len). Equivalent to &self[begin .. len] or &mut self[begin .. len].

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 begin does not point to the starting byte offset of a character (as defined by is_char_boundary), or if begin > len.

type Output = str

The output type returned by methods.

fn get(
    self,
    slice: &str
) -> Option<&<RangeFrom<usize> as SliceIndex<str>>::Output>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, if in bounds.

fn get_mut(
    self,
    slice: &mut str
) -> Option<&mut <RangeFrom<usize> as SliceIndex<str>>::Output>

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, if in bounds.

unsafe fn get_unchecked(
    self,
    slice: *const str
) -> *const <RangeFrom<usize> as SliceIndex<str>>::Output

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, without performing any bounds checking. Calling this method with an out-of-bounds index or a dangling slice pointer is undefined behavior even if the resulting reference is not used.

unsafe fn get_unchecked_mut(
    self,
    slice: *mut str
) -> *mut <RangeFrom<usize> as SliceIndex<str>>::Output

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, without performing any bounds checking. Calling this method with an out-of-bounds index or a dangling slice pointer is undefined behavior even if the resulting reference is not used.

fn index(self, slice: &str) -> &<RangeFrom<usize> as SliceIndex<str>>::Output

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a shared reference to the output at this location, panicking if out of bounds.

fn index_mut(
    self,
    slice: &mut str
) -> &mut <RangeFrom<usize> as SliceIndex<str>>::Output

🔬This is a nightly-only experimental API. (slice_index_methods)

Returns a mutable reference to the output at this location, panicking if out of bounds.

impl<Idx> Eq for RangeFrom<Idx>where
    Idx: Eq,

impl<A> FusedIterator for RangeFrom<A>where
    A: Step,

impl<T> OneSidedRange<T> for RangeFrom<T>where
    RangeFrom<T>: RangeBounds<T>,

impl<Idx> StructuralEq for RangeFrom<Idx>

impl<Idx> StructuralPartialEq for RangeFrom<Idx>

impl<A> TrustedLen for RangeFrom<A>where
    A: TrustedStep,