Using Sum & Inject

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Recently I solved a problem on HackerRank requiring that I calculate and print the sum of the elements in an array. One way of getting the answer would be using each like below:

a = [1, 2, 3]
sum = 0

a.each do |i|
sum += i
end
sum
=> 6

Considering that the elements inside the array above aren’t complicated, the code snippet can be shortened to a more simplistic level by using these methods: sum or inject .

Sum

According to Ruby-Doc.org, this method returns the sum of elements in an enumerable. It continues to say that if a block is given, it is applied to each element before addition. The syntax goes as follows:

enumerable.sum { | obj| block }

So if we use the example from earlier, it should look like this:

a.sum { |i| sum + i }
=> 6

As you can see, it looks so much cleaner and of course, you still get the same result.

Inject

According to Ruby-Doc.org, this method combines all the elements of the enumerable by applying binary operations, such as +, —, *, and / . It is then specified by either a block or symbol that names a method or operator. The syntax goes as follows:

enumerable.inject (inital_value) { |result, obj| block }

So if we again use the example above, it should look like this:

a.inject { |sum, i| sum + i }
=> 6

Yet again, we have cleaner code by using another built-in method.

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Enumerable

Enumerable