What is infinity in Ruby?
It’s something that has a starting point but no ending.
In Ruby, we can express this concept of infinity with the Float::INFINITY constant.
You may be wondering how this is useful.
Let me explain with examples!
Infinity As A Result Of Arithmetic Operations
Ruby returns an Infinity object, as the result of certain math operations.
For example:
You may be familiar with the “division by zero” error.
Here it is:
1/0 # ZeroDivisionError: divided by 0
But…
If you use a float, you get something else:
1/0.0 # Infinity
Infinity!
But that’s not all.
If you try a division of 0 by 0.0, then you get another special value.
Take a look:
0/0.0 # NaN
What is this NaN?
It means “Not a Number”, and as far as I know, this is the only place in Ruby where you’ll find this value.
Why is this a thing?
It’s part of the IEEE 754 Specification, which explains how floating-point operations should behave.
Btw, there are some related methods:
nan?finite?infinite?
You can use these methods to check for special values.
These methods are available on Floats.
Since Ruby 2.4 you can also use finite? & infinite? with Integers.
How to Create Infinite Ranges
Ok.
That was interesting… let’s see more examples.
Now with Ranges!
Here’s an infinite range:
(1..Float::INFINITY).take(10) # [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
This can be helpful when you don’t know the end of the range in advance.
One problem…
It only works with numbers as the starting value.
Example:
("a"..Float::INFINITY)
# ArgumentError: bad value for range
What’s the solution?
With Ruby 2.6, you can do this:
("a"..).take(5)
# ["a", "b", "c", "d", "e"]
Yes, that’s not a mistake! This range has no ending value, only a starting value of "a", then two dots .. to make it a never-ending range.
This is new syntax.
Use Ruby 2.6+ if you want this to work.
Infinity As Maximum & Minimum Value
Another practical use for Infinity?
Well…
It’s the biggest (Infinity) & smallest (-Infinity) number in Ruby.
You can use this as a starting value.
Here’s an example:
def smallest_percent_size(style, ary_size)
@smallest_percent ||= Float::INFINITY
if style == :percent && ary_size < @smallest_percent
@smallest_percent = ary_size
end
@smallest_percent
end
This code is from Rubocop, an open-source project.
Here's how it works:
We are trying to find the smallest array size, but we need a starting value for that because using nil would give you an error.
You could type a big number & hope that's enough.
Or you can use Float::INFINITY, knowing that's that biggest number possible.
Summary
You have learned about infinity in Ruby, what it is, where it may show up & how to use it.
Please share this article so more people can benefit from it.
Thanks for reading!