<![CDATA[QP School - Ruby 3 Tutorials, exercises and examples]]> https://qomplainerzschool.lima-city.de/ Mon, 13 Apr 2026 02:38:12 +0000 MyBB <![CDATA[Everything you need to know about Ruby]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=5056 Tue, 25 Jul 2023 11:53:14 +0200 Qomplainerz]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=5056
Object-Oriented: Ruby is a fully object-oriented language, meaning everything in Ruby is an object, including numbers, strings, and even classes. It follows the principles of object-oriented programming (OOP), such as encapsulation, inheritance, and polymorphism.

Dynamic Typing: Ruby is dynamically-typed, which means you don't need to explicitly declare the data type of a variable. The type of a variable is determined at runtime.

Interpreted Language: Ruby is an interpreted language, which means that code is executed directly without the need for a separate compilation step.

Readable and Expressive Syntax: Ruby's syntax is designed to be readable and expressive, making it easy to write and understand code. It is often praised for its clean and natural language-like constructs.

Gems and RubyGems: Ruby has a rich ecosystem of third-party libraries and tools, known as "gems." RubyGems is the package manager for Ruby that allows developers to easily install, manage, and share these gems.

Rails Framework: Ruby on Rails, often referred to as just Rails, is a popular web application framework built on top of Ruby. Rails follows the Model-View-Controller (MVC) architecture and provides conventions to streamline web development.

Blocks and Procs: Ruby supports blocks and procs, which are anonymous functions that can be passed as arguments to methods. They enable powerful functional programming constructs in the language.

Metaprogramming: Ruby is known for its strong support of metaprogramming, allowing developers to modify and extend the behavior of classes and objects during runtime.

Community and Culture: Ruby has a vibrant and welcoming community. The Ruby community values open-source contributions, collaboration, and sharing knowledge.

Cross-Platform: Ruby is a cross-platform language, which means it runs on various operating systems, including Windows, macOS, and Linux.

Standard Library: Ruby comes with a robust standard library that provides a wide range of built-in classes and modules for common tasks like file I/O, networking, and data processing.

Maturity and Stability: Ruby has been around for several decades and has a stable and mature codebase, which makes it reliable for building production-grade applications.

Ruby is used in a wide range of applications, from web development to scripting and automation. It is known for its "developer-friendly" approach, allowing developers to focus on their code logic rather than boilerplate syntax. The combination of Ruby's readability, flexibility, and community support has made it a favorite language for many developers worldwide.]]>
Object-Oriented: Ruby is a fully object-oriented language, meaning everything in Ruby is an object, including numbers, strings, and even classes. It follows the principles of object-oriented programming (OOP), such as encapsulation, inheritance, and polymorphism.

Dynamic Typing: Ruby is dynamically-typed, which means you don't need to explicitly declare the data type of a variable. The type of a variable is determined at runtime.

Interpreted Language: Ruby is an interpreted language, which means that code is executed directly without the need for a separate compilation step.

Readable and Expressive Syntax: Ruby's syntax is designed to be readable and expressive, making it easy to write and understand code. It is often praised for its clean and natural language-like constructs.

Gems and RubyGems: Ruby has a rich ecosystem of third-party libraries and tools, known as "gems." RubyGems is the package manager for Ruby that allows developers to easily install, manage, and share these gems.

Rails Framework: Ruby on Rails, often referred to as just Rails, is a popular web application framework built on top of Ruby. Rails follows the Model-View-Controller (MVC) architecture and provides conventions to streamline web development.

Blocks and Procs: Ruby supports blocks and procs, which are anonymous functions that can be passed as arguments to methods. They enable powerful functional programming constructs in the language.

Metaprogramming: Ruby is known for its strong support of metaprogramming, allowing developers to modify and extend the behavior of classes and objects during runtime.

Community and Culture: Ruby has a vibrant and welcoming community. The Ruby community values open-source contributions, collaboration, and sharing knowledge.

Cross-Platform: Ruby is a cross-platform language, which means it runs on various operating systems, including Windows, macOS, and Linux.

Standard Library: Ruby comes with a robust standard library that provides a wide range of built-in classes and modules for common tasks like file I/O, networking, and data processing.

Maturity and Stability: Ruby has been around for several decades and has a stable and mature codebase, which makes it reliable for building production-grade applications.

Ruby is used in a wide range of applications, from web development to scripting and automation. It is known for its "developer-friendly" approach, allowing developers to focus on their code logic rather than boilerplate syntax. The combination of Ruby's readability, flexibility, and community support has made it a favorite language for many developers worldwide.]]> <![CDATA[Additions in Ruby]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=3313 Sun, 14 Mar 2021 11:13:51 +0100 Qomplainerz]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=3313 The easiest way to do additions in Ruby is done by passing the values as follows:


Quote: Wrote:puts 3 + 2


The output on the screen will be 5.

Another way is storing the values in variables and then adding one variable to the other as follows:


Quote: Wrote:num1 = 3
num2 = 2
res1 = num1 + num2
puts res1


The output on the screen will be 5, too.

In case we don't already know the values that should be added
we can ask the user to give us the numbers,
store the user inputs in variables
and then add one variable to another as follows:


Quote: Wrote:puts "Please enter a number here: "
num1 = gets.chomp.to_i
puts "Please enter another number here: "
num2 = gets.chomp.to_i
res1 = num1 + num2
puts res1


Now the output will depend on the user input.
Assumed the user typed 3 first and 2 later the result will be 5 as well.]]> The easiest way to do additions in Ruby is done by passing the values as follows:


Quote: Wrote:puts 3 + 2


The output on the screen will be 5.

Another way is storing the values in variables and then adding one variable to the other as follows:


Quote: Wrote:num1 = 3
num2 = 2
res1 = num1 + num2
puts res1


The output on the screen will be 5, too.

In case we don't already know the values that should be added
we can ask the user to give us the numbers,
store the user inputs in variables
and then add one variable to another as follows:


Quote: Wrote:puts "Please enter a number here: "
num1 = gets.chomp.to_i
puts "Please enter another number here: "
num2 = gets.chomp.to_i
res1 = num1 + num2
puts res1


Now the output will depend on the user input.
Assumed the user typed 3 first and 2 later the result will be 5 as well.]]> <![CDATA[Subtractions in Ruby]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=3308 Mon, 08 Mar 2021 12:42:02 +0100 Qomplainerz]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=3308

Quote:puts 3 - 2


The output on the screen will be 1.

Another way is storing the values in variables and then subtracting one variable from the other as follows:


Quote:num1 = 3
num2 = 2
res1 = num1 - num2
puts res1


The output on the screen will be 1, too.

In case we don't already know the values that should be subtracted
we can ask the user to give us the numbers,
store the user inputs in variables
and then subtract one variable from another as follows:


Quote:puts "Please enter a number here: "
num1 = gets.chomp.to_i
puts "Please enter another number here: "
num2 = gets.chomp.to_i
res1 = num1 - num2
puts res1


Now the output will depend on the user input.
Assumed the user typed 3 first and 2 later the result will be 1 as well.]]>

Quote:puts 3 - 2


The output on the screen will be 1.

Another way is storing the values in variables and then subtracting one variable from the other as follows:


Quote:num1 = 3
num2 = 2
res1 = num1 - num2
puts res1


The output on the screen will be 1, too.

In case we don't already know the values that should be subtracted
we can ask the user to give us the numbers,
store the user inputs in variables
and then subtract one variable from another as follows:


Quote:puts "Please enter a number here: "
num1 = gets.chomp.to_i
puts "Please enter another number here: "
num2 = gets.chomp.to_i
res1 = num1 - num2
puts res1


Now the output will depend on the user input.
Assumed the user typed 3 first and 2 later the result will be 1 as well.]]> <![CDATA[Predecessor in Ruby]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2508 Sun, 28 Feb 2021 11:31:03 +0100 Qomplainerz]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2508

Quote:puts 1.pred


This will print 0 on the screen]]>

Quote:puts 1.pred


This will print 0 on the screen]]> <![CDATA[Successor in Ruby]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2507 Sun, 28 Feb 2021 11:29:50 +0100 Qomplainerz]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2507

Quote:puts 1.succ


This will print 2 on the screen]]>

Quote:puts 1.succ


This will print 2 on the screen]]> <![CDATA[Greatest common divisor and least common multiple in Ruby]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2506 Sun, 28 Feb 2021 10:13:53 +0100 Qomplainerz]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2506 To get the greatest common divisor and the least common multiple of 2 numbers at the same time 
we can use the gcd_lcm function instead of gcd and lcm in two separated functions.
In this example we want to know the greatest common divisor 
and the least common multiple of 36 and 60.


Quote:num1 = 36
num2 = 60
gcd_lcm = num1.gcd_lcm(num2)

puts gcd_lcm


This will print 12 and 180 in two lines on the screen.]]> To get the greatest common divisor and the least common multiple of 2 numbers at the same time 
we can use the gcd_lcm function instead of gcd and lcm in two separated functions.
In this example we want to know the greatest common divisor 
and the least common multiple of 36 and 60.


Quote:num1 = 36
num2 = 60
gcd_lcm = num1.gcd_lcm(num2)

puts gcd_lcm


This will print 12 and 180 in two lines on the screen.]]> <![CDATA[Least common multiple in Ruby]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2505 Sun, 28 Feb 2021 10:11:19 +0100 Qomplainerz]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2505 To get the least common multiple of 2 numbers we can use the lcm function.
In this example we want to know the least common multiple of 36 and 60.


Quote:num1 = 36
num2 = 60
lcm = num1.lcm(num2)

puts lcm


This will print 180 on the screen.]]> To get the least common multiple of 2 numbers we can use the lcm function.
In this example we want to know the least common multiple of 36 and 60.


Quote:num1 = 36
num2 = 60
lcm = num1.lcm(num2)

puts lcm


This will print 180 on the screen.]]> <![CDATA[Greatest common divisor in Ruby]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2504 Sun, 28 Feb 2021 10:09:40 +0100 Qomplainerz]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2504 In this example we want to know the greatest common divisor of 36 and 60.


Quote:num1 = 36
num2 = 60
gcd = num1.gcd(num2)

puts gcd


This will print 12 on the screen.]]> In this example we want to know the greatest common divisor of 36 and 60.


Quote:num1 = 36
num2 = 60
gcd = num1.gcd(num2)

puts gcd


This will print 12 on the screen.]]> <![CDATA[Floor and precisions in Ruby]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2503 Sun, 28 Feb 2021 09:40:16 +0100 Qomplainerz]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2503 Let's assume our number is 12.12 and we want to print the floor without any precision:


Quote:puts 12.12.floor


This will print 12 on the screen

Example 2
Let's assume our number is 12.12 and we want to print the floor with a precision of 1 decimal place:


Quote:puts 12.12.floor(1)


This will print 12.1 on the screen

Example 3
Let's assume our number is 12.12 and we want to print the floor with a precision of 2 decimal places:


Quote:puts 12.12.floor(2)


This will print 12.12 on the screen]]> Let's assume our number is 12.12 and we want to print the floor without any precision:


Quote:puts 12.12.floor


This will print 12 on the screen

Example 2
Let's assume our number is 12.12 and we want to print the floor with a precision of 1 decimal place:


Quote:puts 12.12.floor(1)


This will print 12.1 on the screen

Example 3
Let's assume our number is 12.12 and we want to print the floor with a precision of 2 decimal places:


Quote:puts 12.12.floor(2)


This will print 12.12 on the screen]]> <![CDATA[Ceil and precisions in Ruby]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2502 Sun, 28 Feb 2021 09:35:35 +0100 Qomplainerz]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2502 Let's assume our number is 1.1 and we want to print the ceil without any precision:


Quote:puts 1.1.ceil


This will print 2 on the screen, because 1.1 is rounded up to the next whole number.

Example 2:
Let's assume our number is 1.1 and we want to print the ceil with a precision of 1 decimal place:


Quote:puts 1.1.ceil(1)


This will print 1.1 on the screen, because 1.1 is rounded to the nearest 1st. decimal place.

Example 3:
Let's assume our number is 1.1 and we want to print the ceil with a precision of 2 decimal places:


Quote:puts 1.1.ceil(2)


This will print 1.11 on the screen, because 1.1 is rounded to the nearest 2nd decimal place.]]> Let's assume our number is 1.1 and we want to print the ceil without any precision:


Quote:puts 1.1.ceil


This will print 2 on the screen, because 1.1 is rounded up to the next whole number.

Example 2:
Let's assume our number is 1.1 and we want to print the ceil with a precision of 1 decimal place:


Quote:puts 1.1.ceil(1)


This will print 1.1 on the screen, because 1.1 is rounded to the nearest 1st. decimal place.

Example 3:
Let's assume our number is 1.1 and we want to print the ceil with a precision of 2 decimal places:


Quote:puts 1.1.ceil(2)


This will print 1.11 on the screen, because 1.1 is rounded to the nearest 2nd decimal place.]]> <![CDATA[Checking if a number is odd or even in Ruby]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2501 Sun, 28 Feb 2021 09:28:40 +0100 Qomplainerz]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2501 Let's see if 1 is even by executing the following code:


Quote:puts 1.even?


This will print "false" on the screen, because 1 is not even.

Example 2.
Let's see if 2 is even by executing the following code:


Quote:puts 2.even?


This will print "true" on the screen, because 2 is even.

Example 3.
Let's see if 1 is odd by executing the following code:


Quote:puts 1.odd?


This will print "true" on the screen, because 1 is odd.

Example 4.
Let's see if 2 is odd by executing the following code:


Quote:puts 2.odd?


This will print "false" on the screen, because 2 is not odd.]]> Let's see if 1 is even by executing the following code:


Quote:puts 1.even?


This will print "false" on the screen, because 1 is not even.

Example 2.
Let's see if 2 is even by executing the following code:


Quote:puts 2.even?


This will print "true" on the screen, because 2 is even.

Example 3.
Let's see if 1 is odd by executing the following code:


Quote:puts 1.odd?


This will print "true" on the screen, because 1 is odd.

Example 4.
Let's see if 2 is odd by executing the following code:


Quote:puts 2.odd?


This will print "false" on the screen, because 2 is not odd.]]> <![CDATA[Quotients and remainders in Ruby]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2499 Sat, 27 Feb 2021 09:51:41 +0100 Qomplainerz]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2499 official Ruby 3.0.0 documentation I have discovered another cool thing.
Let's assume we want to get the result of 11 / 3 and declare some variables as follows:


Quote:Num1 = 11
Num2 = 3
Quotient = Num1 / Num2
puts "Quotient: " + Quotient.to_s


This will print 3 on the screen.

Now let's get the remainder of the division as follows:


Quote:Option 1: 
Num1 = 11
Num2 = 3
Remainder = Num1 % Num2
puts "Remainder: " + Remainder.to_s

Option 2:
Num1 = 11
Num2 = 3
Remainder = Num1.remainder(Num2)
puts "Remainder: " + Remainder.to_s


Both will print 2 on the screen.

And then let's put the quotient and the remainder together as follows:


Quote:Num1 = 11
Num2 = 3
Quotient = Num1 / Num2
Remainder = Num1 % Num2
Quotient_Remainder = "#{Quotient}, #{Remainder}"
puts "Quotient and remainder: " + Quotient_Remainder.to_s


This will print 3, 2 on the screen.

And now the cool thing.
When using the divmod function Ruby will calculate the quotient and the remainder at the same time.


Quote:Num1 = 11
Num2 = 3
Quotient_Remainder = Num1.divmod(Num2)
puts "Quotient and remainder: " + Quotient_Remainder.to_s


This will print [3, 2] on the screen.]]> official Ruby 3.0.0 documentation I have discovered another cool thing.
Let's assume we want to get the result of 11 / 3 and declare some variables as follows:


Quote:Num1 = 11
Num2 = 3
Quotient = Num1 / Num2
puts "Quotient: " + Quotient.to_s


This will print 3 on the screen.

Now let's get the remainder of the division as follows:


Quote:Option 1: 
Num1 = 11
Num2 = 3
Remainder = Num1 % Num2
puts "Remainder: " + Remainder.to_s

Option 2:
Num1 = 11
Num2 = 3
Remainder = Num1.remainder(Num2)
puts "Remainder: " + Remainder.to_s


Both will print 2 on the screen.

And then let's put the quotient and the remainder together as follows:


Quote:Num1 = 11
Num2 = 3
Quotient = Num1 / Num2
Remainder = Num1 % Num2
Quotient_Remainder = "#{Quotient}, #{Remainder}"
puts "Quotient and remainder: " + Quotient_Remainder.to_s


This will print 3, 2 on the screen.

And now the cool thing.
When using the divmod function Ruby will calculate the quotient and the remainder at the same time.


Quote:Num1 = 11
Num2 = 3
Quotient_Remainder = Num1.divmod(Num2)
puts "Quotient and remainder: " + Quotient_Remainder.to_s


This will print [3, 2] on the screen.]]> <![CDATA[Getting accurate results when working with integers in Ruby]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2498 Sat, 27 Feb 2021 08:35:15 +0100 Qomplainerz]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2498 official Ruby 3.0.0 documentation I have discovered that there are 2 ways to get the square root of a number.
When working with small numbers, both options return the same results,
but when the numbers get bigger the results of Option 2 may be inaccurate as follows:

Option 1:


Quote:Num1 = Integer.sqrt(10**46)
puts Num1


This will put exactly 100000000000000000000000 on the screen.

Option 2:


Quote:Num1 = Math.sqrt(10**46).floor
puts Num1


This will put 99999999999999991611392 on the screen.]]> official Ruby 3.0.0 documentation I have discovered that there are 2 ways to get the square root of a number.
When working with small numbers, both options return the same results,
but when the numbers get bigger the results of Option 2 may be inaccurate as follows:

Option 1:


Quote:Num1 = Integer.sqrt(10**46)
puts Num1


This will put exactly 100000000000000000000000 on the screen.

Option 2:


Quote:Num1 = Math.sqrt(10**46).floor
puts Num1


This will put 99999999999999991611392 on the screen.]]> <![CDATA[Executing Ruby in a Linux terminal]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2497 Sat, 27 Feb 2021 08:28:06 +0100 Qomplainerz]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2497 The Linux version of Ruby doesn't offer the interactive ruby shell,
so if you want to execute Ruby codes from the built in Linux terminal you have to do the following:

1. Open the terminal
2. Write some Ruby code in it
3. Save the file i.e. as example.rb
4. Open the file from the terminal]]> The Linux version of Ruby doesn't offer the interactive ruby shell,
so if you want to execute Ruby codes from the built in Linux terminal you have to do the following:

1. Open the terminal
2. Write some Ruby code in it
3. Save the file i.e. as example.rb
4. Open the file from the terminal]]> <![CDATA[The difference between print and puts]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2496 Fri, 26 Feb 2021 09:28:06 +0100 Qomplainerz]]> https://qomplainerzschool.lima-city.de/showthread.php?tid=2496 For example:


Quote:print 1 + 2
print 2 + 3


This will print the results 3 5 in one line on the screen.

Puts will print whatever you have in a new line on the screen.
For example:


Quote:puts 1 + 2
puts 2 + 3


This will print the results
3
5
in two lines on the screen.]]> For example:


Quote:print 1 + 2
print 2 + 3


This will print the results 3 5 in one line on the screen.

Puts will print whatever you have in a new line on the screen.
For example:


Quote:puts 1 + 2
puts 2 + 3


This will print the results
3
5
in two lines on the screen.]]>