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Ruby Ruby Enumerable

Posted by jack daniel
jack daniel
191 Points

About array inject

You specify about array inject

array = [1,2,3,4,5,6] array.inject {|sum, element| sum =+ element}

will return the sum of all elements in the array because the variable sum is kept between iterations and on the next itiration sum is added again with its previous value to the current element

This is fine.

But why does this work as well?

array.inject {|sum, element| sum + element}

Here we are not storing the result of sum + element in the sum variable but it somehow still returns the correct value?

Why?

1 Answer

Alexander Davison
Alexander Davison
65,469 Points
Alexander Davison
Alexander Davison
65,469 Points

Both work. The block you pass into inject expects you to return a value, and it doesn't matter if you modify it in place. But, remember that sum += element returns sum + element as well as modifying in place the value of sum. Therefore, their return values are equivalent, and the return value is returned from the block. I'm not sure why Jason used += instead of +, because the first one is much more confusing (are you trying to modify in place??)