Using Instance Variable to do Calculation

Question

So I want to use instance variables to do something like

@array.each {|x,y|x+y}

It doesn't seem to be working, and I'm wondering if that is the correct syntax to use with an instance variable, or should it be something like

@array.each |x, y| x+y

or

@array.each [|x,y| x+y]

Do I need to use yield for this?

Answer 1

In general terms, there's no difference between a local and a instance variable, except for its scope. You can use it the very same way.

The problem with your code is that there's no each with two variables (x and y, in your example) for arrays.

You can do either:

total = 0
@array.each { |x| total += x }

Or:

total = @array.inject(0) { |tot, x| tot += x }

Or:

total = @array.inject { |tot, x| tot += x }

Which can be written also like this:

total = @array.inject(:+)

Answer 2

You should have only one variable within the block:

@array.each { |x| ... }

The method each will traverse the array one by one.

Answer 3

You are looking for inject:

@array.inject(:+)

Answer 4

If you want to sum the elements (which seems to be your purpose).

@array.inject(:+)