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Ruby Interview Questions and Answers

Top 100 Ruby Interview Questions for Freshers

Ruby is an essential programming language for web development, with its clear and concise syntax and powerful frameworks like Ruby on Rails. Mastering Ruby for web development can be a key asset in securing a Web Designer role at IDM TechPark, as many tech companies utilize Ruby on Rails for backend development in conjunction with frontend technologies. This guide will help you understand the fundamentals of Ruby and how you can apply it to web development projects.

What is Ruby?
Answer: A high-level, interpreted, object-oriented programming language.
What are variables in Ruby?
Answer: Containers used to store data, dynamically typed.
What are the different types of variables in Ruby?
Answer: Local, Instance, Class, Global.
What are the basic data types in Ruby?
Answer: Integer, String, Float, Boolean, Array, Hash, Nil.
What is a block in Ruby?
Answer: A chunk of code passed to methods for execution.
What is a symbol in Ruby?
Answer: An immutable string-like object used for identifiers or keys in hashes.
How do you define a method in Ruby?
Answer: Using the def keyword.
What is the difference between nil and false in Ruby?
Answer: nil represents "no value", while false is a boolean value.
What is an array in Ruby?
Answer: An ordered collection of elements.
How do you define a class in Ruby?
Answer: Using the class keyword.
What are loops in Ruby?
Answer: Control structures that repeat a block of code.
What is an object in Ruby?
Answer: An instance of a class that encapsulates data and behavior.
How do you handle exceptions in Ruby?
Answer: Using begin..rescue..end.
What is a hash in Ruby?
Answer: A collection of key-value pairs.
What is the difference between puts and print in Ruby?
Answer: puts adds a newline, print does not.
What is the self keyword in Ruby?
Answer: Refers to the current object or context.
How do you create a range in Ruby?
Answer: Using .. (inclusive) or ... (exclusive).
What is the difference between .. and ... in Ruby?
Answer: .. includes the end value, ... excludes it.
What are constants in Ruby?
Answer: Variables that cannot be reassigned, usually in uppercase.
What are the basic methods in Ruby for string manipulation?
Answer: length, upcase, downcase, reverse.
How do you concatenate strings in Ruby?
Answer: Using + or <<.
What is the purpose of the each method in Ruby?
Answer: Iterates over collections.
What is a while loop in Ruby?
Answer: Repeats code while a condition is true.
How can you access a specific element from an array in Ruby?
Answer: Using index notation: arr[index].
How do you define a constructor in Ruby?
Answer: Using the initialize method.

What is inheritance in Ruby?

Answer: A class inherits methods and attributes from another class.
Explain method overloading in Ruby.

Answer: Ruby does not support method overloading directly; variable arguments can be used instead.
What are mixins in Ruby?

Answer: Modules that are included into classes to share functionality.
What is the purpose of super in Ruby?

Answer: Calls a method from the parent class.
What is the difference between class and module in Ruby?

Answer: Classes can be instantiated, modules cannot.
How do you define a getter and setter method in Ruby?

Answer: Using attr_reader, attr_writer, or attr_accessor.
Explain the self keyword within a class method.

Answer: Refers to the class object when used inside a class method.
What are Ruby gems?

Answer: Pre-built libraries to extend Ruby's functionality.
What is the purpose of require and require_relative in Ruby?

Answer: require loads external files, require_relative loads files relative to the current file.
What is a proc in Ruby?

Answer: A block of code that is stored as an object and can be executed later.
What is the purpose of lambda in Ruby?

Answer: A proc that checks the number of arguments and behaves like a method.
How do you handle multiple exceptions in Ruby?

Answer: Using multiple rescue blocks.
What is the to_s method in Ruby?

Answer: Converts an object into a string.
What is the difference between == and equal? in Ruby?

Answer: == compares values, equal? compares object identity.
What are Enumerable methods in Ruby?

Answer: Methods like map, select, reduce that operate on collections.
What is the purpose of include in Ruby?

Answer: To include a module’s methods into a class.
How do you create a singleton method in Ruby?

Answer: By defining a method on a specific object using def object.method.
What is the difference between dup and clone in Ruby?

Answer: dup creates a shallow copy, clone creates a copy with more features, including frozen state.
What is the initialize method in Ruby?

Answer: It’s a special method that is automatically called when a new object is created.
What does self refer to inside a method?

Answer: The current object that the method is called on.
How can you use default arguments in Ruby methods?

Answer: By assigning a default value to a parameter.
What is the purpose of yield in Ruby?

Answer: It calls a block of code passed to a method.
What is a class variable in Ruby?

Answer: A variable that is shared by all instances of a class, prefixed with @@.
What does the defined? operator do in Ruby?

Answer: Checks if a variable, method, or constant is defined.
What are Proc and Lambda differences?

Answer: A lambda checks the number of arguments, and a proc does not.

What is metaprogramming in Ruby?

Answer: Writing code that writes other code, usually at runtime.
How does Ruby handle memory management?

Answer: Through automatic garbage collection.
What is the purpose of method_missing in Ruby?

Answer: It is called when an object receives a method that does not exist.
How do you implement multi-threading in Ruby?

Answer: Using the Thread class.
What is the difference between private and protected methods in Ruby?

Answer: private methods cannot be called by any object, while protected methods can be called within the same class or subclasses.
What is the purpose of define_method in Ruby?

Answer: Dynamically defines a method at runtime.
What is the freeze method in Ruby?

Answer: It prevents an object from being modified.
What is the Benchmark module in Ruby?

Answer: It is used for measuring and comparing the execution time of Ruby code.
How can you prevent inheritance of a class in Ruby?

Answer: By using freeze on the class or making the class final.
What is a Singleton class in Ruby?

Answer: A class that allows only one instance to exist.
What is a callback in Ruby?

Answer: A method that is automatically called at specific points during the lifecycle of an object or process.
How do you handle concurrency in Ruby?

Answer: Using threads, fibers, or the concurrent-ruby gem.
How do you create a gem in Ruby?

Answer: By using the gem command to generate a new gem and writing the gem’s functionality.
What is an abstract class in Ruby?

Answer: Ruby does not have a specific concept for abstract classes, but it can be mimicked using raise NotImplementedError in a method.
How can you create a custom exception in Ruby?

Answer: By subclassing the StandardError class.
What is the purpose of autoload in Ruby?

Answer: Automatically loads a file when it is first referenced.
What is an Enumerator in Ruby?

Answer: An object that can iterate over a collection of items lazily.
What is inject method in Ruby?

Answer: A method that combines elements of a collection into a single value based on a block.
What is the difference between call and yield in Ruby?

Answer: call invokes a proc or lambda, while yield calls a block passed to a method.
What is the binding object in Ruby?

Answer: It represents the execution context, allowing access to variables and methods in the current scope.
How do you define a custom iterator in Ruby?

Answer: By using each with yield in a method.
What are Proc objects and how are they used in Ruby?

Answer: Proc objects are blocks of code that can be passed around and executed later.
How does Ruby support duck typing?

Answer: Ruby checks for the presence of methods and properties rather than checking for specific types.
How do you create a thread-safe class in Ruby?

Answer: By using mutexes or other synchronization mechanisms.
What is Class.new in Ruby?

Answer: A method that creates a new class dynamically at runtime.

What is the difference between Proc and Lambda in Ruby?
Answer: A lambda checks the number of arguments passed, while a proc does not. Also, a lambda returns control to the caller when done, but a proc does not.
What is the purpose of yield in Ruby?
Answer: yield transfers control from a method to a block of code passed to that method.
How does Ruby handle memory management?
Answer: Ruby uses garbage collection to automatically manage memory by reclaiming unused memory.
What is the purpose of method_missing in Ruby?
Answer: It allows you to handle calls to methods that do not exist in an object, enabling dynamic behavior.
What is the difference between public, private, and protected methods in Ruby?
Answer: public methods can be called from anywhere, private methods can only be called within the same object, and protected methods can be called within the same class or subclasses.
How do you handle concurrency in Ruby?
Answer: Using threads, fibers, or the concurrent-ruby gem.
What is the difference between require and require_relative in Ruby?
Answer: require loads external libraries or gems, while require_relative loads files relative to the current file.
What is a singleton class in Ruby?
Answer: A singleton class allows only one instance of a class to exist and can be used to define methods that are specific to that instance.
How can you define default values for method parameters in Ruby?
Answer: By assigning default values directly in the method definition: def method(arg = default_value).
What is the purpose of self in Ruby?
Answer: self refers to the current object, or the context in which a method is called.
How do you implement memoization in Ruby?
Answer: By storing the result of expensive method calls and returning the stored result when the method is called again.
What is the use of define_method in Ruby?
Answer: It dynamically defines methods at runtime.
What is the purpose of block_given? in Ruby?
Answer: It checks if a block is passed to a method.
How do you create a class with a custom initialize method in Ruby?
Answer: By defining the initialize method inside a class to set up instance variables when a new object is created.
How do you handle exceptions in Ruby?
Answer: By using begin..rescue..end blocks.
How do you access a specific element from an array in Ruby?
Answer: Using the index notation: array[index].
What is the each_with_index method in Ruby?
Answer: It iterates over an array while providing both the element and its index in the block.
How do you compare two objects for equality in Ruby?
Answer: Using == for value equality and equal? for object identity comparison.
How do you create a custom iterator in Ruby?
Answer: By defining a method that uses yield to pass elements to the block.
What is the purpose of autoload in Ruby?
Answer: It automatically loads a file when a constant or method is first accessed.
How do you define a constant in Ruby?
Answer: By naming the variable in all uppercase letters: MY_CONSTANT = 100.
How do you prevent a class from being inherited in Ruby?
Answer: By freezing the class with freeze or using finalize techniques.
How do you remove an element from an array in Ruby?
Answer: Using methods like delete, delete_at, or reject.
What is autoload used for in Ruby?
Answer: It loads files only when a specified constant or class is first used.
What is the significance of initialize method in Ruby classes?
Answer: It is called automatically when a new object of a class is created and is used to set initial values for object attributes.