No variable is ever declared in Ruby. Rather, the rule is that a variable must appear in an assignment before it is used. Again, the variable input is assigned before it is used in the puts call.

Used declare variables within a class. There are two main types: class variables, which have the same value across all class instances (i.e. static variables), and instance variables, which have different values for each object instance.

Ruby Class Variables Class variables begin with @@ and must be initialized before they can be used in method definitions. Referencing an uninitialized class variable produces an error. Class variables are shared among descendants of the class or module in which the class variables are defined.

In Ruby, @@ before a variable means it’s a class variable. What you need is the single @ before the variable to create an instance variable. When you do Result….2 Answers

1. attr_accessor : creates the setter and getter methods.
2. attr_reader : create the getter method.
3. attr_writer : create the setter method.

In object-oriented programming with classes, a class variable is any variable declared with the static modifier of which a single copy exists, regardless of how many instances of the class exist. It is a special type of class attribute (or class property, field, or data member).

Instance Variable: It is basically a class variable without a static modifier and is usually shared by all class instances. Class Variable: It is basically a static variable that can be declared anywhere at class level with static. Across different objects, these variables can have only one value.

Variable names in Ruby can be created from alphanumeric characters and the underscore _ character. A variable cannot begin with a number. This makes it easier for the interpreter to distinguish a literal number from a variable. Variable names cannot begin with a capital letter.

Class variables − Class variables also known as static variables are declared with the static keyword in a class, but outside a method, constructor or a block. There would only be one copy of each class variable per class, regardless of how many objects are created from it.

Class Variables In the case of the Bicycle class, the instance variables are cadence , gear , and speed . Each Bicycle object has its own values for these variables, stored in different memory locations. Sometimes, you want to have variables that are common to all objects. This is accomplished with the static modifier.

The proper way to determine the “type” of an object, which is a wobbly term in the Ruby world, is to call object. class . Since classes can inherit from other classes, if you want to determine if an object is “of a particular type” you might call object.

There are different types of variables in Ruby:

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

What is the difference between class variables and class instance variables? The main difference is the behavior concerning inheritance: class variables are shared between a class and all its subclasses, while class instance variables only belong to one specific class.

Ruby variables are locations which hold data to be used in the programs. Each variable has a different name. These variable names are based on some naming conventions. Unlike other programming languages, there is no need to declare a variable in Ruby. A prefix is needed to indicate it.

Global Variables are variables that may be accessed from anywhere in the program regardless of scope. They’re denoted by beginning with a $ (dollar sign) character. However, the use of global variables is often considered “un-Ruby,” and you will rarely see them.

Ruby Variables. Variable is a symbol or name that stands for a value. Variables locate in memory locations and are used to store values such as numeric values, characters, character strings, or memory addresses so that they can be used in any part of the program.

Class variable. In object-oriented programming with classes, a class variable is any variable declared with the static modifier of which a single copy exists, regardless of how many instances of the class exist.