Learning ruby - day 1

Table of Contents

1. Introduction
2. Content
3. Conclusion

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

Ok let's do it

---

Create my first program in ruby

print "Hello World!!!"

Output

PS D:\Workplace> ruby hello-world.rb
Hello World!!!

print "\n" equals puts

print "First line "
print "still first line\n"
puts "Second line"
puts "Thirld line"

Output

First line still first line
Second line
Thirld line

---

Everything is object

print else

Output

main

---

Call Object Method

check whether the num is even or odd

num = 2
print num.even?

Output

true

---

Call Object Method Parameters

print the quotient of num and 2

num = 2
num.div 2
print num

Output

1

---

First loop

print the value of each member in array to the power of 2

array = [1, 2, 3, 4, 5]
array.each do |num|
    puts num.pow 2
end

Output

1
4
9
16
25

---

First function

print ASCII chars of any decimal number in array if number is not odd

def print_char(array)
    array.each do |num|
        puts num.chr unless num.odd?
    end
end
array = [65, 66, 67, 68, 69, 70, 71]
print_char(array)

Output

B
D
F

---

Array

Working on single element

Delete last element

arr.pop

Delete first element

arr.shift

Delete element at position a given position

arr.delete_at(2)

Working on multiple elements

Delete all occurrences of a given element

arr.delete(5)

Delete elements if

arr.delete_if {|a| a < 2}

Delete elements unless

arr.keep_if {|a| a < 4}  

Create subarray

Select elements from array to subarray

arr2 = arr.select {|a| a > 2}
print arr2

Reject elements from array to subarray

arr2 = arr.reject {|a| a > 2}

Reject elements from array till returns false for the first time

arr2 = arr.drop_while {|a| a > 1}

---

Hash, a dictionary-like data structures

# initialize and set default value
empty_hash = Hash.new 
empty_hash.default = 1
# or
default_hash = Hash.new(1)

Set value

new_hash = {"key1" => 12, "key2" => 50}
# or
new_hash = Hash.new
new_hash["key1"] = 12
new_hash["key2"] = 50
# or
new_hash.store("key1", 12)
new_hash.store(1512032, 50)

Loop with hash

hash.each do |key, value|
    puts key
    puts value
end
# or
hash.each do |array|
    # now key is array[0], value is array[1]
    puts array[0]
    puts array[1]
end

Delete pair

# Delete specific key
hash.delete("key1")
# Delete if
hash.keep_if {|key, value| key.is_a? Integer} 
# or 
hash.delete_if {|key, value|key.even? }

---

Infinite Loop

i = 0
loop do
    puts i
    i += 1
    break if i == 10
end

Output

1
2
3
4
5
6
7
8
9
10

---

Conclusion

We have learned how to print output

How to do some basic loop and function

Learned some common methods of array and a dictionary-like data structures called hash

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