problem = 7 + 3
puts problem.to_s
I'm new to Ruby. The code above returns 10. How do I get 7 + 3 as the output, without assigning it to problem as a string in the first place? Am I missing something extremely simple?
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"I'm new to Ruby" – well, this is how evaluation and assignment works in virtually any programming language: the result is being assigned. What are you trying to achieve?Stefan– Stefan2021-08-05 16:27:24 +00:00Commented Aug 5, 2021 at 16:27
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@Stefan: if I were to guess, a simple "solve this equation" game.Sergio Tulentsev– Sergio Tulentsev2021-08-05 20:43:39 +00:00Commented Aug 5, 2021 at 20:43
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3 Answers
Am I missing something extremely simple?
Yes, you are. This is impossible. 7 + 3, as an arbitrary expression, is evaluated/"reduced" to 10 when it's assigned to problem. And the original sequence of calculations is lost.
So you either have to start with strings ("7 + 3") and eval them when you need the numeric result (as @zswqa suggested).
Or package them as procs and use something like method_source.
Comments
just for fun (don't try at home)
class Integer
def +(other)
"#{self} + #{other}"
end
end
problem = 7 + 3
puts problem.to_s # "7 + 3"
2 Comments
Sergio Tulentsev
No need for that
.to_s, though. Also, don't try it at work. :)
Cary Swoveland
This answer is correct, reflects the only way to obtain the desired result and illustrates the folly of doing so. I like.
7 is Fixnum (ruby < 2.4) or Integer (ruby >= 2.4)
"7" is String
So you need to define for ruby what you need because + for Integer is addition, + for String is concatenation:
problem = "7" "+" "3"
That is equal to:
problem = "7+3"
4 Comments
tNJipNJR
That doesn't work for me, unfortunately. As I stated in the question, I want to keep
problem in num + operator + num form for use in other parts of my program.
zswqa
eval(problem) for calculating string. But that is bad practicetNJipNJR
Got you. Thanks for helping!
zswqa
@tNJipNJR Welcome on SO! Do not forget to accept answer that was useful for you.