Determining type of an object?

Ruby Common Questions
1

How do you get the type of an object in ruby?

2

There are many ways to convert a number to a string in Ruby.

The most common way is to use the to_s method:

1.to_s # => "1"
2.to_s # => "2"

The to_s method can also be used with a base argument to convert a number to a string in a different base:

10.to_s(2) # => "1010"
10.to_s(8) # => "12"
10.to_s(10) # => "10"
10.to_s(16) # => "a"

If you need to convert a number to a floating point string, you can use the to_f method:

1.to_f # => 1.0
2.to_f # => 2.0

If you need to convert a number to a rational string, you can use the to_r method:

1.to_r # => (1/1)
2.to_r # => (2/1)

If you need to convert a number to a complex string, you can use the to_c method:

1.to_c # => (1+0i)
2.to_c # => (2+0i)
3

There are no primitive types in Ruby - hence, there’s no typeof. Everything is an object in Ruby, some of the things can be a module, while the rest are instance of classes. To determine the class, we simply use .class() method on the object.

Anything has the .class() method. For example:

> 'hello'.class` # => String
> 'hello'.class.class # => Class
> 5.class # => Integer
> Module.class # => Class
> Class.class # => Class
> { }.class # => Hash
> Class.new { define_method(:x) { 5 } }.new.class # => #<Class:0x000055c793e9ea70>
> X = Class.new { } ; X.new.class # => X
> x = Class.new { } ; x.new.class # => #<Class:0x000055c793517a10>

And so on. It works on all Objects.

2 Likes
4

SouravGoswami is of course right.

However. The correct answer to the original question is (in Ruby): β€œWhy do you want to know?”

There is not much to gain from knowing the class or type of an object. Close to nothing, actually …, apart from finding help on using some class.

When you program Ruby, you first purge your brain of all the remains of any other programming-universes that you may have been exploring. Forget it all.

Then, when you need to know what you can do with a specific object, you ask exactly that question.
I translate:
English – β€œHey object! Can you interate over all your elements, provided there are any?”
Ruby – object.respond_to?(:each)

Ξ© End-Of-Story