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Ruby

Ruby #

variables are #{varname}

Searching a string #

"[Luke:] I can’t believe it. [Yoda:] That is why you fail.".include? 'Yoda'

Searching specific char in string #

"I am a Rubyist".index 'R'

Checking string that starts/ends with: #

"Ruby is a beautiful language".start_with? 'Ruby'
"I can't work with any other language but Ruby".end_with? 'Ruby'

It is conventional in Ruby to have '?' at the end of the method if that method returns only boolean values.

String: lowercase to uppercase etc, swap cases and split #

puts 'i am in lowercase'.upcase
'This is Mixed CASE'.downcase
"ThiS iS A vErY ComPlEx SenTeNcE".swapcase
'Fear is the path to the dark side'.split

Concatenating Strings (3 ways to do it) #

'Ruby' + 'Monk'
"Ruby".concat("Monk")
"Ruby" << "Monk"

Replacing substring (first occurence only) #

"I should look into your problem when I get time".sub('I','We')
output: We should look into your problem when I get time

Replacing substring (all occurences ) #

"I should look into your problem when I get time".gsub('I','We')

Replace all vowels in string with the number 1 (REGEX) #

'RubyMonk'.gsub(/[aeiou]/,'1')
output: R1byM1nk

Replace all capital letters in string with the number 0 (REGEX) #

'RubyMonk Is Pretty Brilliant'.gsub(/[RMIPB]/, '0')
output: 0uby0onk 0s 0retty 0rilliant

Finding chars in a string (REGEX) (used when you don't know what you're looking for) #

'RubyMonk Is Pretty Brilliant'.match(/ ./)
output: I

Boolean expressions #

name == "Bob"

Is age less than or equal to 35 ? #

age <= 35

Is age greater than or equal to 23 and name is 'Bob' OR 'Jill' ? #

age >= 23 && (name == 'Bob' || name == 'Jill')

Name is not Bob #

! (name == 'Bob')

IF / ELSE #

def check_sign(number)
if number > 0
"#{number} is positive"
else
"#{number} is negative"
end
end

If number is 0 #

def check_sign(number)
if number == 0
number
elsif number > 0
"#{number} is positive"
else
"#{number} is negative"
end
end

basically ^^ #

if
do this and that
elsif
something different.
else
none of the above worked. this is where it finally ends.
end

Unless #

age = 10
unless age >= 18
puts "Sorry, you need to be at least eighteen to drive a car. Grow up fast!"
end

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