Find value in an array

If you're trying to determine whether a certain value exists inside an array, you can use Array#include?(value):

a = [1,2,3,4,5]
a.include?(3)   # => true
a.include?(9)   # => false

If you mean something else, check the Ruby Array API

Using Array#select will give you an array of elements that meet the criteria. But if you're looking for a way of getting the element out of the array that meets your criteria, Enumerable#detect would be a better way to go:

array = [1,2,3]
found = array.select {|e| e == 3} #=> [3]
found = array.detect {|e| e == 3} #=> 3

Otherwise you'd have to do something awkward like:

found = array.select {|e| e == 3}.first

If you want find one value from the Array, use Array#find:

arr = [1,2,6,4,9] 
arr.find {|e| e % 3 == 0}   #=>  6

If you want to find multiple values from the Array, use Array#select:

arr.select {|e| e % 3 == 0} #=> [ 6, 9 ]
e.include? 6              #=> true

To find if a value exists in an Array you can also use #in? when using ActiveSupport. #in? works for any object that responds to #include?:

arr = [1, 6]
6.in? arr                 #=> true