# 1.0.0[−][src]Struct std::ops::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 });

Run

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

ⓘThis example deliberately fails to compile

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

Run

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    ]);  // 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  ]);

Run

## Fields

`end: Idx`

The upper bound of the range (exclusive).

## Methods

### `impl<Idx> RangeTo<Idx> where
Idx: PartialOrd<Idx>,` [src]

#### `pub fn contains<U>(&self, item: &U) -> bool where
Idx: PartialOrd<U>,
U: PartialOrd<Idx> + ?Sized,` 1.35.0[src]

Returns `true` if `item` is contained in the range.

# Examples

    use std::f32;

    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));

Run

## Trait Implementations

### `impl<Idx> Clone for RangeTo<Idx> where
Idx: Clone,` [src]

#### `fn clone(&self) -> RangeTo<Idx>`[src]

Returns a copy of the value. Read more

#### `fn clone_from(&mut self, source: &Self)`[src]

Performs copy-assignment from `source`. Read more

### `impl<Idx> Copy for RangeTo<Idx> where
Idx: Copy,` [src]

### `impl<Idx> Debug for RangeTo<Idx> where
Idx: Debug,` [src]

#### `fn fmt(&self, fmt: &mut Formatter) -> Result<(), Error>`[src]

Formats the value using the given formatter. Read more

### `impl<Idx> Eq for RangeTo<Idx> where
Idx: Eq,` [src]

### `impl<Idx> Hash for RangeTo<Idx> where
Idx: Hash,` [src]

#### `fn hash<__H>(&self, state: &mut __H) where
__H: Hasher,` [src]

Feeds this value into the given [`Hasher`]. Read more

#### `fn hash_slice<H>(data: &[Self], state: &mut H) where
H: Hasher,` 1.3.0[src]

Feeds a slice of this type into the given [`Hasher`]. Read more

### `impl Index<RangeTo<usize>> for String`[src]

#### `type Output = str`

The returned type after indexing.

#### `fn index(&self, index: RangeTo<usize>) -> &str`[src]

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

### `impl IndexMut<RangeTo<usize>> for String` 1.3.0[src]

#### `fn index_mut(&mut self, index: RangeTo<usize>) -> &mut str`[src]

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

### `impl<Idx> PartialEq<RangeTo<Idx>> for RangeTo<Idx> where
Idx: PartialEq<Idx>,` [src]

#### `fn eq(&self, other: &RangeTo<Idx>) -> bool`[src]

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

#### `fn ne(&self, other: &RangeTo<Idx>) -> bool`[src]

This method tests for `!=`.

### `impl<'_, T> RangeBounds<T> for RangeTo<&'_ T>`1.28.0[src]

#### `fn start_bound(&self) -> Bound<&T>`[src]

Start index bound. Read more

#### `fn end_bound(&self) -> Bound<&T>`[src]

End index bound. Read more

#### `fn contains<U>(&self, item: &U) -> bool where
T: PartialOrd<U>,
U: PartialOrd<T> + ?Sized,` 1.35.0[src]

Returns `true` if `item` is contained in the range. Read more

### `impl<T> RangeBounds<T> for RangeTo<T>`1.28.0[src]

#### `fn start_bound(&self) -> Bound<&T>`[src]

Start index bound. Read more

#### `fn end_bound(&self) -> Bound<&T>`[src]

End index bound. Read more

#### `fn contains<U>(&self, item: &U) -> bool where
T: PartialOrd<U>,
U: PartialOrd<T> + ?Sized,` 1.35.0[src]

Returns `true` if `item` is contained in the range. Read more

### `impl<T> SliceIndex<[T]> for RangeTo<usize>`1.15.0[src]

#### `type Output = [T]`

The output type returned by methods.

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

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

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

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

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

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

#### `unsafe fn get_unchecked(self, slice: &[T]) -> &[T]`[src]

🔬 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 is [undefined behavior] even if the resulting reference is not used. [undefined behavior]: ../../reference/behavior-considered-undefined.html Read more

#### `unsafe fn get_unchecked_mut(self, slice: &mut [T]) -> &mut [T]`[src]

🔬 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 is [undefined behavior] even if the resulting reference is not used. [undefined behavior]: ../../reference/behavior-considered-undefined.html Read more

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

🔬 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. Read more

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

🔬 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. Read more

### `impl SliceIndex<str> for RangeTo<usize>`1.20.0[src]

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`.

#### `type Output = str`

The output type returned by methods.

#### `fn get(
self,
slice: &str
) -> Option<&<RangeTo<usize> as SliceIndex<str>>::Output>`[src]

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

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

#### `fn get_mut(
self,
slice: &mut str
) -> Option<&mut <RangeTo<usize> as SliceIndex<str>>::Output>`[src]

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

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

#### `unsafe fn get_unchecked(
self,
slice: &str
) -> &<RangeTo<usize> as SliceIndex<str>>::Output`[src]

🔬 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 is [undefined behavior] even if the resulting reference is not used. [undefined behavior]: ../../reference/behavior-considered-undefined.html Read more

#### `unsafe fn get_unchecked_mut(
self,
slice: &mut str
) -> &mut <RangeTo<usize> as SliceIndex<str>>::Output`[src]

🔬 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 is [undefined behavior] even if the resulting reference is not used. [undefined behavior]: ../../reference/behavior-considered-undefined.html Read more

#### `fn index(self, slice: &str) -> &<RangeTo<usize> as SliceIndex<str>>::Output`[src]

🔬 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. Read more

#### `fn index_mut(
self,
slice: &mut str
) -> &mut <RangeTo<usize> as SliceIndex<str>>::Output`[src]

🔬 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. Read more

### `impl<Idx> StructuralEq for RangeTo<Idx>`[src]

### `impl<Idx> StructuralPartialEq for RangeTo<Idx>`[src]

## Auto Trait Implementations

### `impl<Idx> RefUnwindSafe for RangeTo<Idx> where
Idx: RefUnwindSafe,`

### `impl<Idx> Send for RangeTo<Idx> where
Idx: Send,`

### `impl<Idx> Sync for RangeTo<Idx> where
Idx: Sync,`

### `impl<Idx> Unpin for RangeTo<Idx> where
Idx: Unpin,`

### `impl<Idx> UnwindSafe for RangeTo<Idx> where
Idx: UnwindSafe,`

## Blanket Implementations

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `fn type_id(&self) -> TypeId`[src]

Gets the `TypeId` of `self`. Read more

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `fn borrow(&self) -> &T`[src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `fn borrow_mut(&mut self) -> &mut T`[src]

Mutably borrows from an owned value. Read more

### `impl<T> From<T> for T`[src]

#### `fn from(t: T) -> T`[src]

Performs the conversion.

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `fn into(self) -> U`[src]

Performs the conversion.

### `impl<T> ToOwned for T where
T: Clone,` [src]

#### `type Owned = T`

The resulting type after obtaining ownership.

#### `fn to_owned(&self) -> T`[src]

Creates owned data from borrowed data, usually by cloning. Read more

#### `fn clone_into(&self, target: &mut T)`[src]

🔬 This is a nightly-only experimental API. (`toowned_clone_into` #41263)

recently added

Uses borrowed data to replace owned data, usually by cloning. Read more

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

#### `fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>`[src]

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

#### `type Error = <U as TryFrom<T>>::Error`

The type returned in the event of a conversion error.

#### `fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>`[src]

Performs the conversion.