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!