Ruby += assignment operator

Question

foo = [10,20,30,40,50,60]
foo_total = 0
foo.each do |f|
 print foo_total += f
end
print foo_total

The output of this code sample will be 10 30 60 100 150 210 210 but I'm actually looking for 10 20 30 40 50 60 210 I know that it can be achieved by using the following code

foo = [10,20,30,40,50,60]
foo_total = 0
foo.each do |f|
 print f
 foo_total += f
end
print foo_total

However, is there a more elegant approach that needs just one line in the foo.each block?

edit: It's not only about the output, but also about having the variable foo_total that contains the sum of all values in foo

I suppose you could use an abomination like print (foo_total += f) - f. — Cary Swoveland
– Cary Swoveland, Commented Feb 5, 2014 at 17:57
print f; foo_total +=f would be one line, but not one statement. — MxLDevs
– MxLDevs, Commented Feb 5, 2014 at 18:00

Arup Rakshit · Accepted Answer · 2014-02-05 18:05:51Z

1

Do as below

(arup~>~)$ pry --simple-prompt
>> foo = [10,20,30,40,50,60]
=> [10, 20, 30, 40, 50, 60]
>> foo.push(foo.inject(:+))
=> [10, 20, 30, 40, 50, 60, 210]
>>

edited Feb 5, 2014 at 18:05

answered Feb 5, 2014 at 17:50

Arup Rakshit

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4 Comments

Brian Over a year ago

Just to enhance, since OP seems to be looking for a string: foo.join(' ')

the Tin Man Over a year ago

I doubt the OP wants a string. Using print will result in the values being output on a single line in the console, but nowhere is there an indication that the array should be joined or "stringified" in any way.

Tolsto Over a year ago

@theTinMan is right. I want to print each number in foo and also have the variable foo_total that contains the sum of all values in foo

Brian Over a year ago

My bad, sorry folks (I should not be commenting on SO on low sleep) :-)

Uri Agassi · Accepted Answer · 2014-02-05 18:10:54Z

1

How about:

foo.each do |f|
  foo_total += f.tap { |f1| print f1 }
end

answered Feb 5, 2014 at 18:10

Uri Agassi

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1 Comment

Cary Swoveland Over a year ago

+1 for anything with tap, though I doubt you'd use this just to save a line of code. (I love the sound of that method. tap.tap.tap is even better.)

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