Ruby Array API

Appends each given object to self. Returns self (with aliases <<).

a = [1, 2]
a.push(3)
a.push(4, 5)
# a == [1, 2, 3, 4, 5]
a << 6
# a == [1, 2, 3, 4, 5, 6]

Removes and returns the last element of self, or nil if the array is empty.

a = [1, 2, 3]
x = a.pop  # 3
# a == [1, 2]

Returns the number of elements in self. Alias: size.

[1, 2, 3].length  # 3
[].size           # 0

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

[1, 2, 3].each { |x| puts x }
# prints:
# 1
# 2
# 3

Returns a new array containing the values returned by the block for each element. Alias: collect.

[1, 2, 3].map { |x| x * x }  # [1, 4, 9]

Returns a new array containing all elements for which the block returns a truthy value.

[1, 2, 3, 4].select { |x| x.even? }  # [2, 4]

Returns true if the given object is present in self, false otherwise.

[1, 2, 3].include?(2)  # true
[1, 2, 3].include?(9)  # false

Returns the concatenation of all elements converted to strings, joined by separator.

["a", "b", "c"].join("-")  # "a-b-c"
[1, 2, 3].join(", ")      # "1, 2, 3"