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Roman Pushkin
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1 changed files with 87 additions and 9 deletions
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@ -2,12 +2,14 @@
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===
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Q: What is one of the principles of Ruby language?
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A: Principle of least surprise
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002
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===
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Q: Which programming language was primarily used to build GitHub, AirBnB, Shopify?
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A: Ruby
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003
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@ -17,15 +19,18 @@ A: Ruby
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===
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Q: Is Ruby dynamically or statically-typed language?
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A: Dynamically
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Q: Which web framework is often used along with Ruby?
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A: Rails
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005
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===
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Q: For which type of software engineering Ruby is often used for?
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A: Web development
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006
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@ -35,102 +40,128 @@ A: Web development
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===
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Q: What works best for your resume and improving your programming skill?
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A: Personal Ruby project
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008
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===
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Q: What is the recommended operating system for a Ruby developer?
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A: Linux or MacOS
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009
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===
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Q: You typed "`ruby`" from the terminal and nothing happens, why?
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A: Ruby interpreter is waiting for your input
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Q: Which key sequence you have to press to indicate the end of input in the terminal?
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Q: Which key sequence you have to press to indicate the end of input in the terminal?
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A: Ctrl+D
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010
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===
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Q: What REPL stands for?
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A: Read, Evaluate, Print Loop
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Q: How do you run default REPL for Ruby?
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A: By typing "`irb`"
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011
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===
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Q: How do you run a Ruby program from the terminal?
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A: `ruby app.rb`
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012
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===
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Q: Why file manager is a useful tool?
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A: Because new Ruby on Rails projects have many files
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A: Because it is easier for a beginner to navigate the file system with arrow keys
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A: Because it is faster to manipulate files and directories
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A: Because it provides visual representation of a file system
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(^all of the answers)
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013
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===
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Q: File system can be represented as a ... ?
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A: tree
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014
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===
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Q: What shell command do we use to change directory in Linux/macOS?
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A: `cd`
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Q: What shell command do we use to change to a _parent_ directory in Linux/macOS?
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A: `cd ..`
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Q: What shell command do we use to list files in current directory?
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Q: What shell command do we use to list files in current directory?
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A: `ls`
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015
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===
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Q: What shell command do we use to show the contents of a file?
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A: `cat file.txt`
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Q: What shell command do we use to make a directory?
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A: `mkdir`
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Q: What shell command do we use to copy files?
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A: `cp`
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Q: What shell command do we use to move files?
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A: `mv`
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016
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===
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Q: What of the following is _not_ a code editor?
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A: Microsoft Word
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(the possible list of answers here, all of them are valid code editors: Visual Studio Code, Vim, Sublime Text, Notepad++)
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017
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===
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Q: What statement do we use to put a string to the console (screen)?
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A: `puts`
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Q: What statement do we use to get a string from the console?
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A: `gets`
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018
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===
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Q: What naming convention is preferred for a variable names in Ruby?
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A: snake_case
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(possible incorrect answers: camelCase, kebab-case)
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@ -138,40 +169,48 @@ A: snake_case
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===
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Q: What is the result of `"1" + "2"` expression in Ruby?
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A: `"12"`
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Q: What is the result of `1 + 2` expression in Ruby?
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A: `3`
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020
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===
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Q: Variable `tmp` is initialized (holds a reference to an object). How do you find out the name of the class for this object?
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A: `tmp.class`
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021
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===
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Q: Everything is ...(select from the list below)... in Ruby.
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A: an object
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022
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===
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Q: What method do we use to convert/coerce a string to an integer?
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A: `to_i`
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Q: What method do we use to convert/coerce an arbitrary object to a string?
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A: `to_s`
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023
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===
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Q: What class is okay to use if we want to represent `3.14` in Ruby for simple calculations?
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A: Float
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(don't provide BigDecimal in the list of answers)
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Q: What class should we use if we want to represent `3.141592653589793238462643383279502884197169399375105820974944592307816406286` in Ruby for precise calculations?
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A: BigDecimal
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(you can add Float as incorrect answer here)
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@ -179,12 +218,14 @@ A: BigDecimal
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===
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Q: Interpolation is ... ?
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A: a handy way to concatenate strings
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025
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===
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Q: Dangerous method of an object is a ...
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A: method to perform operation on the object itself
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(possible incorrect answers: method that should never get called, method that has security vulnerabilities)
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@ -192,9 +233,11 @@ A: method to perform operation on the object itself
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===
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Q: What's the max number of lines of code is allowed in a Ruby block?
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A: no max number, blocks can be as long as they need to be
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Q: Ruby blocks are...
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A: little anonymous functions that can be passed into methods
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@ -202,19 +245,24 @@ A: little anonymous functions that can be passed into methods
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===
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Q: Block parameters are surrounded by this character
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A: pipe
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(possible answers: colon, semicolon)
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(possible answers: colon, semicolon)
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029
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===
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Q: "Testing a variable" (in the context of branching) means
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A: checking if variable equals to a certain value
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Q: We use the following operator to test a variable
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A: `if`
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Q: Testing if variable equals to a certain value can be done with the following operator
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A: `==`
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(possible answers: `=`, `==`, `===`, `is`, `====`)
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@ -222,26 +270,32 @@ A: `==`
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===
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Q: To combine multiple conditions in `if...end` block we can use the following boolean operator
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A: `&&`, `||`, `and`, `or`
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(the correct answer is "all of the above")
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031
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===
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Q: We use this statement to tell Ruby program to wait some amount of time
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A: `sleep`
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032
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===
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Q: What statement should we use to generate a random number from 1 to 10?
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A: `rand(1..10)`
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(on of the possible incorrect answers: `rand(1,10)` or `rand(10)` which will generate numbers from 0 to 9)
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033
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===
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Q: Which program is the correct implementation of an infinite loop?
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A:
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```ruby
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@ -278,6 +332,7 @@ loop(
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===
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Q: Ternary operator is
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A: a short way to write `if...else` statement
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(possible answers: a way to exit a program, a way to wait for some amount of time)
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@ -286,13 +341,16 @@ A: a short way to write `if...else` statement
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===
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Q: What would be the output of the following Ruby program: `puts "100\r500"` ?
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A: `500`
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(possible incorrect answers: 100500, 100, 1500, 10500)
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036
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===
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Q: What's the right syntax to define a method in Ruby?
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A:
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```ruby
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@ -332,11 +390,13 @@ end
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===
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Q: Select the right statement
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A: instance variables have `@` prefix
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(possible incorrect answers: local have `@` prefix)
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Q: Local variables
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A: do not have any prefix
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039
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@ -357,19 +417,21 @@ A: From 0 to 15
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===
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Q: What is the result of `['1', '30', '20', '100'].sort` expression? Why?
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A: `["1", "100", "20", "30"]` (because numbers are strings)
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041
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===
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Q: What method do we use to iterate over an array?
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A: `each`
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A: `each`
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042
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===
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Q: Empty array can be initialized with the following statement
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A: `arr = []`
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(possible incorrect answers: `arr = [0]`, `arr = [-1]`, `arr = ''`)
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@ -390,9 +452,11 @@ A: 9
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===
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Q: What is `%w` syntax in Ruby?
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A: A quick way to define array of strings
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Q: What is `%i` syntax in Ruby?
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A: A quick way to define array of symbols
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045
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@ -405,9 +469,11 @@ A: A quick way to define array of symbols
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===
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Q: Ruby gems are ...
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A: Libraries created by developers from around the world with useful functionality
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Q: To use a Ruby gem you must...
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A: (two correct answers) 1) Install it from the command line 2) `require` gem in your program
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048
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@ -436,7 +502,7 @@ arr = [
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[
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%w(a b c),
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%w(d e f),
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%w(g h i)
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%w(g h i)
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],
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[
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%w(aa bb cc),
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@ -457,9 +523,11 @@ A: beef
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===
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Q: What is the result of `''.empty?` expression?
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A: true
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Q: What is the result of `''.nil?` expression and why?
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A: false, because even empty strings are objects in Ruby (with the type of String), and objects can't be nils.
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052
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@ -597,7 +665,7 @@ students = [
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{ name: 'Pat', age: 18, class: :arts, score: 10 },
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{ name: 'Joe', age: 19, class: :math, score: 1 },
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{ name: 'Ann', age: 20, class: :arts, score: 2 },
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{ name: 'Lev', age: 21, class: :math, score: 3 }
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{ name: 'Lev', age: 21, class: :math, score: 3 }
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]
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students.select { |student| student[:age] >= 18 }.take(2).reject { |student| student[:class] == :math }[0][:name]
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```
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@ -635,10 +703,12 @@ A: false
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===
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Q: Hashes in Ruby are ...
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A: key-value in-memory storage
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(possible incorrect answers: improved version of an array, key-value storage with database backend)
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Q: When program ends, what happens with keys and values of a Ruby hash on the next run?
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A: everything goes away, hash will be empty
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(possible incorrect answers: data remains in the hash and can be reused, only keys are present, only values are present)
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@ -646,6 +716,7 @@ A: everything goes away, hash will be empty
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===
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Q: Hash values are...
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A: objects of any type or nils
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(possible incorrect answers: always string values; always integer values; objects, but not nils)
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@ -653,10 +724,13 @@ A: objects of any type or nils
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===
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Q: Normally JSON structure is...
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A: a mix of hashes, arrays, and simple types, and can be used in Ruby language
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possible incorrect answers:
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* a mix of hashes, arrays, and simple types and cannot be used in Ruby language
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* JavaScript Object Notation, and there is no JSON support in Ruby language
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* JavaScript Object Notation, and there is no JSON support in Ruby language
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065
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===
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@ -681,9 +755,11 @@ A: `Привет, Володя`
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===
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Q: On average, a hash data structure has ... lookup complexity
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A: constant, O(1) - because you don't have to scan the hash to find elements
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A: constant, O(1) - because you don't have to scan the hash to find elements
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Q: Array has ... lookup complexity
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A: linear, O(N) - because you need to scan the N elements in the array to find one element
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067
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@ -733,12 +809,14 @@ A: 256
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===
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Q: When you should prefer hash set over a regular hash?
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A: when there is no need for keeping values in a hash, and you have only keys to add
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071
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===
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Q: While iterating over a hash key-value pairs in Ruby language, the order of inserted elements ...
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A: is guaranteed in the [documentation](https://ruby-doc.org/core-2.2.2/Hash.html), but in other programming languages there is no such guarantee
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072
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@ -979,4 +1057,4 @@ Possible incorrect answers:
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* It's only about convenience and developer happiness, these matchers are interchangeable
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* "Be" means "_equal to, you don't have to be exactly this, just equal is fine_". While "eq" means "_to be exactly this_".
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* It doesn't affect the way the shell works
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Loading…
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