Ruby – Difference between Symbols and Strings

Ruby has Symbols as well as Strings. Their are differences between the two that should be known for proper use in your Application while coding.

Symbols:

First of all, let us take a look at how Symbols are created:

> a = :First_Symbol

The above statement after execution, will create object of Symbol Class.

Let us create one more symbol, say b

$ b = :Second_Symbol

This will again create object of string class.

If we create another symbol, say c, like

> c = :First_Symbol

The, if we see their object id’s:

$ a.object_id
=> 5304108
$ b.object_id
=> 5305708
$ c.object_id
=> 5304108

You must have observed, the object id’s of Symbol a and Symbol c are one and the same. i.e. 5304108

It shows that if symbol with the same name already exists in the memory then the same reference is given to the new object with the same name.

i.e. Multiple Symbol objects with the same name will have same reference.

Strings:

First of all, let us create a object of String class as,

$ x = "Ruby"

Lets us create another String, say y

$ y = "Rails"

Creating one more String, say z

$ z = "Ruby"

Let us print object id’s of all three,

$ x.object_id
=> 70232194795200
$ y.object_id
=> 70232194785680
$ z.object_id
=> 70232194775260

As we can see that, Strings are not given same reference though if we create new strings with same name.

Strings can be concatenated in Ruby, in a bit different way, you can read it here.

There are Performance advantages if one uses Strings and Symbols properly in his code. You can explore various methods on Strings and Symbols by calling _object.methods. _Feel free to explore to get more of these.