HackerRank Ruby Strings Indexing Solution

Hello coders, In this post, you will learn how to solve HackerRank Ruby Strings Indexing Solution. This problem is a part of the Ruby Tutorial series. One more thing to add, don’t straight away look for the solutions, first try to solve the problems by yourself. If you find any difficulty after trying several times, then look for the solutions.

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HackerRank Ruby Strings Indexing Solution
HackerRank Ruby Strings Indexing Solution

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HackerRank Ruby Strings Indexing Solution

Let’s get started with Ruby Strings Indexing Solution

Problem Statement

When you index a string, you extract or alter the portions. This is perhaps the most important operation you want to perform on strings. The string class provides a convenient array-like square bracket [] operator, which allows you to extract portions of the string as well as altering the content when used on the left side of an assignment.

Consider the following examples:

str = “Hello World!”
str[-1] # first character from the end of the string
str[-2] # second last character
str[0] # first character

More often, you’d want to extract specific portions of the string rather than individual characters. To do this, use comma separated operands between the square brackets. The first operand specifies an index (which may be negative), and the second specifies a length (which must be non-negative).

Consider the example below:

str[0,4] # first four characters
str[6,3] # 3 characters starting from index 6 ( 0-indexing )
str[1, 1] # 1 character starting from the END of string

The same examples shown above can be used for assignment / deletion of characters. We can insert characters by giving a non-empty assignment or delete characters in the range by giving an empty assignment.

Consider the example below:

str = “Hello”
str[str.size, 0] = ” World!” # append by assigning at the end of the string
“Hello World!”
str[5, 0] = “,” # insert a comma after the 5th position
str[5, 6] = “” # delete 6 characters starting from index 5.
str[5,1] = ” World” # replace the string starting from index 5 and of length 1 with the given string.

But wait, there’s more! Ruby also allows you to index strings using a Range or a Regexp object as well. We will discuss these methods in the future.

In this challenge, your task is to code a serial_average method which is described below:

  • It takes a fixed width string in format: SSS-XX.XX-YY.YYSSS is a three digit serial number, XX.XX and YY.YY are two digit numbers including up to two decimal digits.
  • It returns a string containing the answer in format SSS-ZZ.ZZ where SSS is the serial number of that input string, and ZZ.ZZ is the average of XX.XX and YY.YY.
  • All numbers are rounded off to two decimal places.

For example:


You can use string interpolation to insert Ruby code within a string.

For example:

tmp = 123
“Hello #{tmp}”
Hello 123


HackerRank Ruby Strings Indexing Solution

def serial_average(str)
   b = str.split('-')

Note: This problem (Ruby – Strings – Indexing) is generated by HackerRank but the solution is provided by Chase2Learn. This tutorial is only for Educational and Learning purpose.


1. What is Ruby programming?

Ruby programming is a high-level, interpreted, general-purpose programming language. It is designed for developing web applications and is known for its fast, concise, and easy-to-learn syntax. Ruby is used by many large tech companies such as Google, Facebook, and Twitter. Read more

2. Should I put HackerRank certificate on resume?

These certificates are useless, and you should not put them on your resume. The experience you gained from getting them is not useless. Use it to build a portfolio, and link to it on your resume. 

3. Can I retake HackerRank test?

The company which sent you the HackerRank Test invite owns your Test submissions and results. It’s their discretion to permit a reattempt for a particular Test. If you wish to retake the test, we recommend that you contact the concerned recruiter who invited you to the Test and request a re-invite. 

4. What is HackerRank?

HackerRank is a tech company that focuses on competitive programming challenges for both consumers and businesses. Developers compete by writing programs according to provided specifications. Wikipedia

5. Where can I find HackerRank Ruby solutions?

in this post, you will get all the solutions to HackerRank ruby Problems.

Finally, we are now, in the end, I just want to conclude some important message for you

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