Table of Contents
Introduction
Hey guys, welcome to my blog recording my ruby self-taught process
I decided to learn this amazing language while I was trying to solving some ruby challenges to get my tenth badge in HackerRank
At the first day, We have gotten to know Ruby. If you found it a little hard to understand then let me know immediately, otherwise I will keep writing this blog as a learning process recording
Today I will focus on more details what we have learned at the first day
Print output
Print value of variable and type of variable
name = "Ade"
puts "Hello #{name}!"
puts "#{name.class.name}"
As we have discussed at the first day "Everything is Object", so we're now able to know that type of variable is a class name
Output
PS D:\Workplace> ruby hello-world.rb
Hello Ade!
String
Print raw version of an object, use for debugging string.
P is a kernel method
a = " \n"
p a
Output
" \n"
Pretty printting, use for print Hash object
json = {
"2019":[
{
"language":"Ruby",
"edition":"seventh"
},
{
"language":"Python",
"edition":"sixth"
},
{
"language":"Oracle",
"edition":"second"
}
],
"2020":[
{
"language":"C++",
"edition":"first"
},
{
"language":"Java",
"edition":"fourth"
},
{
"language":"Mysql",
"edition":"third"
}
]
}
puts json
puts "----------------------------------------------------"
pp json
Output
{:"2019"=>[{:language=>"Ruby", :edition=>"seventh"}, {:language=>"Python", :edition=>"sixth"}, {:language=>"Oracle", :edition=>"second"}], :"2020"=>[{:language=>"C++", :edition=>"first"}, {:language=>"Java", :edition=>"fourth"}, {:language=>"Mysql", :edition=>"third"}]}
----------------------------------------------------
{:"2019"=>
[{:language=>"Ruby", :edition=>"seventh"},
{:language=>"Python", :edition=>"sixth"},
{:language=>"Oracle", :edition=>"second"}],
:"2020"=>
[{:language=>"C++", :edition=>"first"},
{:language=>"Java", :edition=>"fourth"},
{:language=>"Mysql", :edition=>"third"}]}
As you can see, it looks pretty as it name
Too much if - use Case instead
if today == "Monday"
puts "2, 30 July 2021"
elsif today == "Tuesday"
puts "3, 30 July 2021"
#...
else
puts "8, 30 July 2021"
end
case today
when "Monday"
puts "2, 30 July 2021"
when "Tuesday"
puts "3, 30 July 2021"
#...
else
puts "8, 30 July 2021"
end
Output
6, 30 July 2021
Playing with array elements
arr = [65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78]
puts "Array: #{arr.inspect}"
puts "Array length = #{arr.length}"
puts "First element: #{arr[0]}"
puts "First element: #{arr.first}"
puts "Last element: #{arr[-1]}"
puts "Last element: #{arr.last}"
puts "Five first elements #{arr.take(5).inspect}"
puts "Ignores five first elements #{arr.drop(5).inspect}"
puts "Element at index 3 #{arr[3]}"
puts "Elements from index 3 to index 7 #{arr[3..7]}"
puts "Elements from index 3 to index 6 #{arr[3...7]}"
puts "8 Elements from index 3 #{arr[3, 8]}"
Output
Array: [65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78]
Array length = 14
First element: 65
First element: 65
Last element: 78
Last element: 78
Five first elements [65, 66, 67, 68, 69]
Ignores five first elements [70, 71, 72, 73, 74, 75, 76, 77, 78]
Element at index 3 68
Elements from index 3 to index 7 [68, 69, 70, 71, 72]
Elements from index 3 to index 6 [68, 69, 70, 71]
8 Elements from index 3 [68, 69, 70, 71, 72, 73, 74, 75]
inspect help puts print all array elements in one line
Add elements to array
At the last blog, we have learned a bunch of ways to delete elements from array, let's look back a little
arr = [65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78]
puts "Array: \t\t\t#{arr.inspect}"
arr.shift
puts "Delete first element: \t#{arr.inspect}"
arr.pop.inspect
puts "Delete last element: \t#{arr.inspect}"
arr.delete_at(2).inspect
puts "Delete at index 2: \t#{arr.inspect}"
Output
Array: [65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78]
Delete first element: [66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78]
Delete last element: [66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77]
Delete at index 2: [66, 67, 69, 70, 71, 72, 73, 74, 75, 76, 77]
Now we're learning some ways to add elements to array
arr = [65, 66, 67, 68, 69, 70]
puts "Array: \t\t\t#{arr.inspect}"
arr.unshift(97, 98)
puts "Add at first position: \t#{arr.inspect}"
arr.push(254, 255)
puts "Add at last position: \t#{arr.inspect}"
arr.insert(5, 128, 129)
puts "Add at index 5: \t#{arr.inspect}"
Output
Array: [65, 66, 67, 68, 69, 70]
Add at first position: [97, 98, 65, 66, 67, 68, 69, 70]
Add at last position: [97, 98, 65, 66, 67, 68, 69, 70, 254, 255]
Add at index 5: [97, 98, 65, 66, 67, 128, 129, 68, 69, 70, 254, 255]
As you can see we can add more than just one element
Here document
puts 'Starting', '------------', <<HERE, 'Real Ending'
1. Salad mix.
2. Strawberries.
3. Cereal.
4. Milk.
HERE
Output
Starting
------------
1. Salad mix.
2. Strawberries.
3. Cereal.
4. Milk.
Real Ending
This will print 'Starting' and '------------' normally as puts always do
The <<HERE here means the next occurrence of HERE will be the end of this document
'Real Ending' is lying right after the <<HERE, will be print out right after the end of the document
You can set multiple << to exchange words in the document
<<HERE will be failed if there is any space or tab before the next occurrence HERE, <<-HERE is saying the next occurence can have some space, tab or HERE
Please check this link to learn more about this feature
https://en.wikibooks.org/wiki/Ruby_Programming/Here_documents
String
In this part, we're going to talk a little more about string in Ruby
String elements can be called in multiple ways
- Each char
str.each_char {|x| p x}
Output
"W"
"h"
"a"
"t"
"'"
"s"
" "
"u"
"p"
"?"
- Each byte
str.each_byte {|x| p x}
Output
87
104
97
116
39
115
32
117
112
63
- Each line
"hello\nworld".each_line {|s| p s}
Output
"hello\n"
"world"
We can access elements of a string just like how we do with array
But we cannot delete or add elements to string like we do with array or hash
This is how we do it
Remember these methods will just return a new string, it does not change the original string
- Delete last char
str = "Hi \t\r\n"
p str.chop.chop
Output
"Hi "
You can see that we can chop multiple time, \r, \n, \r\n (exept \n\r though) will be treat as one char
- Delete multiple last chars
str = "Hi, My name is Ade\r\n\r"
p str = str.chomp
p str = str.chomp
p str.chomp "Ade"
Output
"Hi, My name is Ade\r\n"
"Hi, My name is Ade"
"Hi, My name is "
Delete \r or \n or \r\n unless there is a parameter
- Delete whitespaces
str = " \r\n\tHi , Are you having fun?\t \r \n"
p str.strip
Output
"Hi , Are you having fun?"
Delete the leading and trailing \t\n\r and whitespaces
- Append str
str = ""
str += "Hello"
# or
str = ""
str << "Ruby is " << "pretty"
# How to append non-string
str << 3.14.to_s
- Add to the beginning
str = "Gimme your wallet"
p str
p str.prepend("Please, ")
Output
"Gimme your wallet"
"Please, Gimme your wallet"
Check text occurs in str with include
str.include? "wallet"
Replace text in str with gsub, first parameter can be RegExp or String, second parameter is string will replace the occurrence texts
str.gsub(/wallet/, heart)
str = "Please, Gimme your wallet"
if str.include? "wallet"
puts str.gsub(/wallet/, "heart")
end
Output
Please, Gimme your heart
Conclusion
We have learned more about printing object
Interesting feature called Here document to print multiple line strings
Acknowledged how to access, add and delete elements in array and string, or as i say "playing around with array and string"
I'd like to thank HackerRank for giving me a chance to acknowledge and be interesting in this cool language
If guys found Ruby is fascinating, please come to the link below and solve some Ruby challenges with me
https://www.hackerrank.com/domains/ruby
If you have any question or suggestion, please let me know at the comment section below.
OK I'm going to wrap this up here
Thanks for reading my blog
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