class Array(T)
Overview
An Array
is an ordered, integer-indexed collection of objects of type T.
Array indexing starts at 0. A negative index is assumed to be relative to the end of the array: -1 indicates the last element, -2 is the next to last element, and so on.
An Array
can be created using the usual new
method (several are provided), or with an array literal:
Array(Int32).new # => []
[1, 2, 3] # Array(Int32)
[1, "hello", 'x'] # Array(Int32 | String | Char)
An Array
can have mixed types, meaning T will be a union of types, but these are determined
when the array is created, either by specifying T or by using an array literal. In the latter
case, T will be set to the union of the array literal elements' types.
When creating an empty array you must always specify T:
[] of Int32 # same as Array(Int32)
[] # syntax error
An Array
is implemented using an internal buffer of some capacity
and is reallocated when elements are pushed to it when more capacity
is needed. This is normally known as a dynamic array.
You can use a special array literal syntax with other types too, as long as they define an argless
new
method and a <<
method. Set
is one such type:
set = Set{1, 2, 3} # => Set{1, 2, 3}
set.class # => Set(Int32)
The above is the same as this:
set = Set(typeof(1, 2, 3)).new
set << 1
set << 2
set << 3
Included Modules
- Comparable(Array(T))
- Indexable(T)
Defined in:
crystal_on_steroids/to_query.crcrystal_on_steroids/array/from.cr
crystal_on_steroids/array/not_last.cr
crystal_on_steroids/array/ordinal.cr
crystal_on_steroids/array/rest.cr
crystal_on_steroids/array/slice.cr
crystal_on_steroids/array/split.cr
crystal_on_steroids/array/to.cr
Instance Method Summary
-
#fifth
Returns the fifth element in an array.
-
#fourth
Returns the fourth element in an array.
-
#from(position : Int)
Returns the tail of the array from
position
. -
#not_last
Returns the elements in an array except the last one.
-
#rest
Returns the elements in an array except the first one.
-
#second
Returns the second element in an array.
-
#slice(index : Int, length : Int) : Array(T)
Array#slice(index : Int, length : Int)
-
#slice(index : Int) : T
Array#slice(index : Int)
-
#slice(range : Range(Int, Int)) : Array(T)
Array#slice(range : Range(Int, Int))
-
#split(value = nil)
Divides the array into one or more subarrays based on a delimiting
value
or the result of an optional block. -
#split(&)
Divides the array into one or more subarrays based on a the result of an optional block.
-
#third
Returns the third element in an array.
-
#to(position : Int)
Returns the beginning of the array up to
position
. -
#to_param
Calls
#to_param
on all its elements and joins the result with slashes. -
#to_query(namespace)
Cast an array as a HTTP::Params and buils an url-encode string.
Instance methods inherited from module Enumerable(T)
avg
avg,
blank?
blank?,
exactly?(count : Int32, &)
exactly?,
excludes?(obj)
excludes?,
frequencies
frequencies,
many?(&)many? many?, pluck(*keys) pluck, pluck?(*keys) pluck?, without(*items) without
Instance methods inherited from class Object
in?(another_object)
in?,
presence
presence,
presence_in(another_object)
presence_in,
present?
present?,
to_param
to_param,
to_query(namespace)to_query to_query
Class methods inherited from class Object
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Instance Method Detail
Returns the tail of the array from position
.
%w( a b c d ).from(0)
=> ["a", "b", "c", "d"]
%w( a b c d ).from(2)
=> ["c", "d"]
%w( a b c d ).from(10)
=> []
%w().from(0)
=> []
%w( a b c d ).from(-2)
=> ["c", "d"]
%w( a b c ).from(-10)
=> []
Returns the elements in an array except the last one.
[1, 2, 3, 4, 5].not_last
=> [1, 2, 3, 4]
Returns the elements in an array except the first one.
[1, 2, 3, 4, 5].rest
=> [2, 3, 4, 5]
Array#slice(index : Int, length : Int)
Returns a sub array starting from the index for the length thats passed.
Array#slice(index : Int)
Returns the element of the array at the passed in Index.
Array#slice(range : Range(Int, Int))
Returns a sub array based on the range passed in.
Divides the array into one or more subarrays based on a delimiting value
or the result of an optional block.
[1, 2, 3, 4, 5].split(3)
=> [[1, 2], [4, 5]]
Divides the array into one or more subarrays based on a the result of an optional block.
(1..10).to_a.split { |i| i % 3 == 0 }
=> [[1, 2], [4, 5], [7, 8], [10]]
Returns the beginning of the array up to position
.
%w( a b c d ).to(0)
=> ["a"]
%w( a b c d ).to(2)
=> ["a", "b", "c"]
%w( a b c d ).to(10)
=> ["a", "b", "c", "d"]
%w().to(0)
=> []
%w( a b c d ).to(-2)
=> ["a", "b", "c"]
%w( a b c ).to(-10)
=> []
Calls #to_param
on all its elements and joins the result with
slashes.
source: Rails ActiveSupport
Cast an array as a HTTP::Params and buils an url-encode string.
["michael", "jhon"].to_query("user")
=> "user%5B%5D=michael&user%5B%5D=jhon"