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Question-1. What is Crystal?
Answer-1: Crystal is a statically typed, compiled programming language inspired by Ruby, designed for performance and concurrency.
Question-2. What are the key features of Crystal?
Answer-2: Crystal offers a Ruby-like syntax, static typing with type inference, high performance, and built-in support for concurrency.
Question-3. How does Crystal handle type inference?
Answer-3: Crystal automatically infers types based on the values assigned, reducing the need for explicit type annotations.
Question-4. How does Crystal compare to Ruby?
Answer-4: Crystal has a Ruby-like syntax but is statically typed, compiled, and much faster due to its compiled nature.
Question-5. How do you define a variable in Crystal?
Answer-5: Variables are defined using var or without explicit types, e.g., name = "Crystal" or age : Int32 = 25.
Question-6. How do you define a method in Crystal?
Answer-6: Methods are defined using the def keyword, e.g., def greet(name : String) : String; "Hello, #{name}"; end.
Question-7. What is Crystal's concurrency model?
Answer-7: Crystal uses fibers, which are lightweight threads, for concurrency.
Question-8. How do you write a loop in Crystal?
Answer-8: Loops can be written using while, until, or iterators like each, e.g., `5.times {
Question-9. What is the purpose of macros in Crystal?
Answer-9: Macros are used for metaprogramming, allowing code generation and manipulation at compile-time.
Question-10. How do you create a class in Crystal?
Answer-10: Classes are created using the class keyword, e.g., class Person; def initialize(name : String); @name = name; end; end.
Question-11. What are modules in Crystal?
Answer-11: Modules are collections of methods and constants, used to share functionality across classes.
Question-12. How do you include a module in a class in Crystal?
Answer-12: Modules are included using the include keyword, e.g., include Comparable.
Question-13. What is the require keyword used for in Crystal?
Answer-13: The require keyword is used to include external libraries or other files into a Crystal program.
Question-14. How do you define an array in Crystal?
Answer-14: Arrays are defined using square brackets, e.g., arr = [1, 2, 3].
Question-15. How do you define a hash in Crystal?
Answer-15: Hashes are defined using curly braces, e.g., hash = {"key" => "value"}.
Question-16. How does Crystal handle exceptions?
Answer-16: Crystal uses begin, rescue, and ensure blocks for exception handling.
Question-17. What are blocks in Crystal?
Answer-17: Blocks are anonymous pieces of code passed to methods, enclosed in {} or do...end.
Question-18. How do you define a constant in Crystal?
Answer-18: Constants are defined using uppercase names, e.g., PI = 3.14.
Question-19. What is Crystal's type system?
Answer-19: Crystal has a static type system with union types and type inference.
Question-20. How do you use generics in Crystal?
Answer-20: Generics are defined using
Question-21. How do you perform string interpolation in Crystal?
Answer-21: String interpolation is done using #{} within double quotes, e.g., "Hello, #{name}".
Question-22. What are fibers in Crystal?
Answer-22: Fibers are lightweight threads that provide concurrency by running tasks cooperatively.
Question-23. How do you handle file I/O in Crystal?
Answer-23: File I/O is handled using the File module, e.g., `File.open("file.txt", "r") do
Question-24. How do you use annotations in Crystal?
Answer-24: Annotations are metadata for methods or classes, used for compile-time directives, e.g., @[Deprecated("Use new_method instead")].
Question-25. How do you implement an interface in Crystal?
Answer-25: Interfaces are implemented using abstract classes or modules with method definitions.
Question-26. What are structs in Crystal?
Answer-26: structs are value types used for lightweight objects, defined using the struct keyword.
Question-27. How do you work with command-line arguments in Crystal?
Answer-27: Command-line arguments are accessed using the ARGV array.
Question-28. How do you define an enum in Crystal?
Answer-28: Enums are defined using the enum keyword, e.g., enum Color; Red; Green; Blue; end.
Question-29. What are shards in Crystal?
Answer-29: Shards are Crystal's package management system, allowing libraries to be easily shared and installed.
Question-30. How do you handle JSON in Crystal?
Answer-30: JSON is handled using the JSON module, e.g., JSON.parse(string) or to_json.
Question-31. What are unions in Crystal?
Answer-31: Unions represent a value that can be of multiple types, e.g., `String
Question-32. What is a nil type in Crystal?
Answer-32: nil represents the absence of a value, similar to null in other languages.
Question-33. How do you use regular expressions in Crystal?
Answer-33: Regular expressions are created using %r(), e.g., regex = %r{[a-z]+}.
Question-34. What is the purpose of the yield keyword in Crystal?
Answer-34: yield passes control from a method to a block provided to the method.
Question-35. How do you define a singleton method in Crystal?
Answer-35: Singleton methods are defined on the metaclass, e.g., def self.method_name; end.
Question-36. How do you handle concurrency in Crystal?
Answer-36: Concurrency is managed using fibers and channels for communication.
Question-37. What is a channel in Crystal?
Answer-37: Channels are used for communication between fibers, providing thread-safe message passing.
Question-38. How do you format strings in Crystal?
Answer-38: Strings are formatted using the sprintf method or interpolation.
Question-39. How do you create custom exceptions in Crystal?
Answer-39: Custom exceptions are created by inheriting from Exception.
Question-40. How does Crystal manage memory?
Answer-40: Crystal uses automatic memory management with a garbage collector.
Question-41. How do you use the select method in Crystal?
Answer-41: select is used with channels to wait for multiple communications.
Question-42. How do you define a range in Crystal?
Answer-42: Ranges are defined using .. or ..., e.g., 1..10.
Question-43. What is the nilable type in Crystal?
Answer-43: A nilable type is a union of nil and another type, e.g., String?.
Question-44. How do you create a library in Crystal?
Answer-44: Libraries are created by defining reusable modules or classes and publishing them as shards.
Question-45. How do you test Crystal code?
Answer-45: Crystal code is tested using the built-in Spec module.
Question-46. How do you write a macro in Crystal?
Answer-46: Macros are written using {% %} for compile-time code evaluation.
Question-47. How do you optimize performance in Crystal?
Answer-47: Performance is optimized by leveraging compile-time checks, static typing, and avoiding runtime type checks.
Question-48. What is the purpose of require "spec" in Crystal?
Answer-48: require "spec" includes the testing framework for writing unit tests.
Question-49. How do you perform type casting in Crystal?
Answer-49: Type casting is done using as, e.g., x = obj as Int32.
Question-50. How do you run a Crystal program?
Answer-50: Crystal programs are run using crystal run filename.cr.
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