[Ruby] How to use slice for beginners


The ** slice ** code came out as an answer with a Ruby drill, and I couldn't understand it easily, so I will leave it as a memorandum.


There are any two strings. Ignore case and select ** True ** if one character is at the end of the other If not, create a program that outputs ** False **. (That is, it is not case sensitive).



def end_other(a,b)
  a_down = a.downcase
  b_down = b.downcase
  a_len = a_down.length
  b_len = b_down.length
  if  a_down.slice!(-(b_len)..a_len - 1) == b_down #← I will explain this line!
    puts "True"
    puts "False"

puts "Please enter the alphabet"
code = gets.chomp

puts "Please enter the characters you specify"
find_word = gets.chomp

end_other(code, find_word)


** slice ** returns the substring after removing the specified range from the string. Was: grin: Reference: https://docs.ruby-lang.org/ja/2.3.0/method/String/i/slice=21.html


string = "this is a string"
string.slice!(2)        #=> "i"
string.slice!(3..6)     #=> " is "
string.slice!(/s.*t/)   #=> "sa st"
string.slice!("r")      #=> "r"

: warning: Count starts from ** 0 (zero) **! I stumbled here: sweat:

Therefore, the above answer can be explained in detail as follows: point_up:


def end_other(a,b)
  a_down = a.downcase  
  #Convert all letters of variable a to lowercase!
  b_down = b.downcase
  #Convert all letters of variable b to lowercase!
  a_len = a_down.length
  #Get the number of characters in variable a!
  b_len = b_down.length
  #Get the number of characters in variable b!
  if  a_down.slice!(-(b_len)..a_len - 1) == b_down
  #-(b_len) :Returns the number of characters from the last character of variable a to the number of characters of variable b
  #a_len - 1 :Returns the last character of the variable a
  #.. :Above, represents the following

It looks like this, but honestly, even myself? ?? ?? So I will actually apply the characters: grinning:

Commentary commentary www

a = wOrD
b = Rd

def end_other(a,b)
  a_down = a.downcase  
  #wOrD ⇒ word
  b_down = b.downcase
  #Rd ⇒ rd
  a_len = a_down.length
  #4 characters
  b_len = b_down.length
  #2 letters
  if  a_down.slice!(-(b_len)..a_len - 1) == b_down
  #-(b_len) :Returns the last two characters of word ...>is r
  #a_len - 1 :Returns the last character of word ...>d
  #a_down.slice!(-(b_len)..a_len - 1) :Will be rd


It may be a little confusing. .. .. .. Sorry for my lack of writing: bow:

I hope it helps you a little: laughing:


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