Why is Ruby concatenating instead of adding 2 values?

Question

I wrote a small program to test out Textmate 2 (I'm fairly new to Ruby) and it's spitting out that 4 + 9 = 49 instead of 13 for some reason.

def add(x,y)
  c = x + y
  return c
end

puts "please enter a value "
a = gets.chomp
puts "please enter another value "
b = gets.chomp

printMe = add(a,b)

puts printMe

A good question to ask at this point is, do you understand the difference between strings and numberics? That "4" + "9" = "49" should have instantly triggered understanding of what happened. — the Tin Man, Jan 28 '12 at 18:05

Vasiliy Ermolovich · Accepted Answer · 2011-12-14T04:02:56.300

7

It's because gets returns a string:

def add(x,y)
  c = x + y
end

puts "please enter a value "
a = gets.to_i
puts "please enter another value "
b = gets.to_i

printMe = add(a,b)

puts printMe

edited Dec 14 '11 at 04:02

answered Dec 13 '11 at 20:02

Vasiliy Ermolovich

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`a = gets.to_i` will do (no chomping). – steenslag Dec 13 '11 at 21:37

score 0 · Answer 2 · answered Dec 13 '11 at 20:04

0

It's treating the input as string by default I guess, try:

def add(x,y)
  (x.to_i + y.to_i)
end

Also, no need to return in ruby or place in variable c, it will automagically return the last line of code as output

answered Dec 13 '11 at 20:04

Rym

650
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16

It's not as convenient or sense-making as the gets.to_i approach. When one supplies add("x", "y"), one would then get a result different from "xy", which would be unexpected a weird. And that's not great for program readability. – bcc32 Dec 13 '11 at 22:24

score 0 · Answer 3 · edited May 23 '17 at 11:48

0

If you did puts printMe.inspect, you'd be able to see for yourself that it's "49", not 49, and that a and b are strings. For more debugging hints, see How do I debug Ruby scripts?

edited May 23 '17 at 11:48

Community

1
1

answered Dec 13 '11 at 22:29

Andrew Grimm

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Why is Ruby concatenating instead of adding 2 values?

3 Answers3