[Solved] Ruby – map vs each?

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The doc suggests:

each { |item| block } → ary click to toggle source
each → Enumerator
Calls the given block once for each element in self, passing that element as a parameter.

And:

map { |item| block } → new_ary click to toggle source map → Enumerator
Invokes the given block once for each element of self.

Creates a new array containing the values returned by the block.

See also Enumerable#collect.

If no block is given, an Enumerator is returned instead.

which actually means that map creates another new array while each simply iterates and does not touch the original array.

An example:

def yeller(array)
 a = array.each(&:upcase)
 puts a
 puts array
 puts "a: " + a.join
 puts "array: " + array.join
 puts "a == array?" + (a==array).to_s
end

yeller(%w[a, b, c])

def yeller(array)
  a = array.map(&:upcase)
  puts a
  puts array
  puts "a: " + a.join
  puts "array: " + array.join
end

yeller(%w[a, b, c])

Result:

a,
b,
c
a,
b,
c
a: a,b,c
array: a,b,c
a == array?true
A,
B,
C
a,
b,
c
a: A,B,C
array: a,b,c

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solved Ruby – map vs each?