[Ruby] Extracting elements with slice method


You can learn the slice method while solving the problem. Previous article summarizes "slice method and slice! Method", so please have a look.

table of contents

--Practice --Problem --Answer (commentary) --Another solution

--Summary --References


You can extract the specified element from a string or array by using the slice method. Since the subscript starts from 0, specify the argument in consideration.


array = [0,1,2,3,4,5,6] #Create an array

array.slice(1..3) #1 of the array~Take out the third
#=> [1, 2, 3]

array.slice(1, 5) #Extract 1 to 5 elements of the array
#=> [1, 2, 3, 4, 5]



Create a method that repeats the last two characters of the string three times and outputs it.

Answer (commentary)


def repeat_char(str)
  char_length = str.length - 2               #I want to get the length of the string and start from the last two characters-Doing 2
  char_slice  = str.slice(char_length, 2)    #Variable char_Extract 2 characters from length
  p char_slice * 3                           #Output 3 times

#Method call

#Terminal output result
# "lelele"
# "gegege"
# "ononon"

Another solution

In order to make the start position ** second ** from the end, in the above example, the length of the character string is obtained and then -2.

Here, it is obtained by specifying -2 as the first argument of slice.

Another solution

def repeat_char(str)
  char_slice  = str.slice(-2, 2)    #The penultimate start
  p char_slice * 3

#Method call


--"Slice" can extract the element specified by the argument from a character string or array. -** The subscript starts from number 0 **, so be careful when taking it out. --By specifying -1 as the first argument of" slice ", you can" get the last "of any ** character string or array **.


-Ruby 3.0.0 Reference Manual (Array # slice)

-Ruby 3.0.0 Reference Manual (String # slice!)

-What is the slice method? Let's solve the example and understand the difference from slice!

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