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

Like this?

a = [ "a", "b", "c", "d", "e" ]
a[2] +  a[0] + a[1]    #=> "cab"
a[6]                   #=> nil
a[1, 2]                #=> [ "b", "c" ]
a[1..3]                #=> [ "b", "c", "d" ]
a[4..7]                #=> [ "e" ]
a[6..10]               #=> nil
a[-3, 3]               #=> [ "c", "d", "e" ]
# special cases
a[5]                   #=> nil
a[5, 1]                #=> []
a[5..10]               #=> []

or like this?

a = [ "a", "b", "c" ]
a.index("b")   #=> 1
a.index("z")   #=> nil

See the manual.

you can use Array.select or Array.index to do that.

Use:

myarray.index "valuetoFind"

That will return you the index of the element you want or nil if your array doesn't contain the value.

This answer is for everyone that realizes the accepted answer does not address the question as it currently written.

The question asks how to find a value in an array. The accepted answer shows how to check whether a value exists in an array.

There is already an example using index, so I am providing an example using the select method.

1.9.3-p327 :012 > x = [1,2,3,4,5]
  => [1, 2, 3, 4, 5] 
1.9.3-p327 :013 > x.select {|y| y == 1}
  => [1]

I know this question has already been answered, but I came here looking for a way to filter elements in an Array based on some criteria. So here is my solution example: using select, I find all constants in Class that start with "RUBY_"

Class.constants.select {|c| c.to_s =~ /^RUBY_/ }

UPDATE: In the meantime I have discovered that Array#grep works much better. For the above example,

Class.constants.grep /^RUBY_/

did the trick.

You can go for array methods.

To see all array methods use methods function with array. For Example,

a = ["name", "surname"] 
a.methods

By the way you can use different method for checking value in array You can use a.include?("name").

Thanks for replies.

I did like this:

puts 'find' if array.include?(value)