Returns the number of times that the passed item is present in the collection.

[1, 2, 3, 4].count(3) # => 1

Returns a shallow copy of this object.

This allocates a new object and copies the contents of self into it.

Calls the given block once for each element in self , passing that element as a parameter.

a = ["a", "b", "c"]
a.each { |x| print x, " -- " }

produces:

a -- b -- c --

Returns true if self is empty, false otherwise.

([] of Int32).empty? # => true
([1]).empty?         # => false

Returns the index of the first appearance of object in self starting from the given offset , or nil if object is not in self .

[1, 2, 3, 1, 2, 3].index(2, offset: 2) # => 4

Returns the index of the first appearance of obj in self starting from the given offset . Raises Enumerable::NotFoundError if obj is not in self .

[1, 2, 3, 1, 2, 3].index!(2, offset: 2) # => 4

Appends a String representation of this object which includes its class name, its object address and the values of all instance variables.

class Person
  def initialize(@name : String, @age : Int32)
  end
end

Person.new("John", 32).inspect # => #<Person:0x10fd31f20 @name="John", @age=32>

Returns the element with the maximum value in the collection.

It compares using > so it will work for any type that supports that method.

[1, 2, 3].max        # => 3
["Alice", "Bob"].max # => "Bob"

Raises Enumerable::EmptyError if the collection is empty.

Like #max but returns nil if the collection is empty.

Returns the element with the minimum value in the collection.

It compares using < so it will work for any type that supports that method.

[1, 2, 3].min        # => 1
["Alice", "Bob"].min # => "Alice"

Raises Enumerable::EmptyError if the collection is empty.

Like #min but returns nil if the collection is empty.

Returns the index of the last appearance of value in self , or nil if the value is not in self .

If offset is given, it defines the position to end the search (elements beyond this point are ignored).

[1, 2, 3, 2, 3].rindex(2)            # => 3
[1, 2, 3, 2, 3].rindex(2, offset: 2) # => 1

Returns the index of the last appearance of value in self , or nil if the value is not in self .

If offset is given, it defines the position to end the search (elements beyond this point are ignored).

[1, 2, 3, 2, 3].rindex(2)            # => 3
[1, 2, 3, 2, 3].rindex(2, offset: 2) # => 1

Raises Enumerable::NotFoundError if value is not in self .

Returns the number of elements in this container.

Returns an Array with all the elements in the collection.

(1..5).to_a # => [1, 2, 3, 4, 5]

Appends a short String representation of this object which includes its class name and its object address.

class Person
  def initialize(@name : String, @age : Int32)
  end
end

Person.new("John", 32).to_s # => #<Person:0x10a199f20>

Returns the element at the given index , without doing any bounds check.

Indexable makes sure to invoke this method with index in 0...size , so converting negative indices to positive ones is not needed here.

Clients never invoke this method directly. Instead, they access elements with #[](index) and #[]?(index) .

This method should only be directly invoked if you are absolutely sure the index is in bounds, to avoid a bounds check for a small boost of performance.

Sets the element at the given index to value , without doing any bounds check.

Indexable::Mutable makes sure to invoke this method with index in 0...size , so converting negative indices to positive ones is not needed here.

Clients never invoke this method directly. Instead, they modify elements with #[]=(index, value) .

This method should only be directly invoked if you are absolutely sure the index is in bounds, to avoid a bounds check for a small boost of performance.