Variables in Ruby

What is a Variable in Ruby?

A variable is a designated storage space for a value or an object reference. Variables are an essential part of any programming language because they allow you to store and manipulate data. Variables in Ruby are dynamically` typed, so you don't have to specify their type before using them.

How to Use Variables in Ruby?

To declare variables, a lowercase letter or underscore is utilized, followed by a combination of letters, numbers, or underscores. The assignment operator ( = ) is used for assigning the values to the variables.

• The variables can be utilized in any section of the code if they are defined or valid in that particular scope of code.
• Variables can be interpolated in strings that is the corresponding value of that variable will replace the placeholder #{variable_name}.
• Variables can be passed as arguments to methods which can then be utilized to store the parameters inside a method for implementing the logic.

Types of Variables in Ruby

Ruby has four types of variables, which are:

• Local variables
• Instance variables
• Class variables
• Global variables

Let's take a closer look at each type of variable and how to use them in your Ruby programs.

Local variables

A local variable is a variable that is defined in a method or block and is only accessible within that method or block. Local variables are denoted by a lowercase letter or underscore at the beginning of the variable name. Here is an example of declaring and using a local variable in Ruby:

In this example, we defined a method called greetings that takes a parameter called name. Inside the method, we declared a local variable called message, which stores a string value that includes the name parameter. We then printed the value of the message variable to the console by interpolating it with a prefix string "Hello".

Instance variables

An instance variable is a variable that is associated with an instance of a class. They are used to store data that is unique to each object created from the same class. They are denoted by the @ symbol at the beginning of the variable name. They are not accessible outside of the class they are defined in. Here is an example of using an instance variable in Ruby:

In this example, we defined a class called Person that has an instance variable called @name. When we create a new instance of the Person class using the new method, we pass in a name parameter that is used to initialize the @name instance variable. We then call the greetings method on the person instance, which prints a message to the console that includes the value of the @name instance variable.

Class variables

A class variable is a variable that is defined in a class and is accessible to all the instances of that class. Class variables are denoted by two @@ symbols at the beginning of the variable name. Like instance variables, they are not accessible outside of the class. Here is an example of declaring and using a class variable in Ruby:

In this example, we defined a class Person that has a class variable called @@count, which is initialized to 0, a constructor method that initializes the instance variable @name and increments the @@count variable by 1 and a class method count that returns the value of the @@count variable.

Global variables

A global variable is a variable that can be accessed from anywhere in a Ruby program. Global variables are denoted by the $ symbol at the beginning of the variable name. Here is an example of declaring and using a global variable in Ruby:

In this example, we defined two methods called setName and greetings. Inside the setName method, we declared a global variable called $name, which stores the value of the name parameter. We then defined a method called greetings, which prints a greeting that includes the $name variable.