First Ruby Program

Learn to create and execute the first Ruby program.

We'll cover the following

Problem solving with Ruby

The basic tools for understanding the flow and the results of simple programs are execution sheetsAn execution sheet is a manual way of observing and updating the values of the variables at each step of the execution of a program. and flowchartsA flowchart is a diagram that helps understand the sequence of instructions in a program having decision.. However, they become complicated when we have problems with a large number of decisions. Therefore we provide executable embedded code widgets to observe the program output by executing it.

Note: We can rerun a program as many times as we want, to try outputs for different inputs or values of variables.

In Ruby, we use gets for input (to read a value from the user).

Hello World

It’s time to write our first program in Ruby, which will simply display the message “Hello World!” on the screen.

This is the code widget that we’ll use to write our Ruby code. We can execute our Ruby program by clicking the “Run” button at the bottom of the widget:

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print "Hello World!" # Printing Hello World!

Note: We can add non-executable text in a Ruby program by adding a hash sign (#) at the start of the text. This type of text is called a comment. We use comments to include descriptions in the program.

The program below is the same as the one above and has the same output. The only exception is that we use parentheses with the print statement in the below program. Using () with print does not affect the output of the code, but it does make it easy to read.

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print("Hello World!") # Printing Hello World! while using parentheses with print

Add a new line in the output

We can break a sentence into multiple sentences by using "\n" in the print() statement. The string, "\n", introduces a new line when used in the print statement.

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print("Single")
print("Line\n")
print("Separate New Line\n")

Personalize messages and add variables

In the following program, we store a string in a variable, name, and output it using a print() statement inside #{}. We can use #{} to output variables in the print statement. The operator, #{}, performs expression substitution in the string and is not part of the output itself.

Note: A variable name can only contain letters (A–Z and a–z) and the underscore symbol (_). It may also contain digits (0–9), but the variable name can’t start with those. For example, Key_2 is a valid variable name but 2_key is not. Variable names are case-sensitive, meaning that name, Name, and NAME are three different variables.

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name = "Educative"
print("Hello User. Welcome to #{name}")

Let’s write another Ruby program that inputs the name of the user before displaying a greeting message. We use the name as a variable to store the input given by the user in Ruby.

main.rb in the left pane of the following widget is the name of the program file. .rb indicates that it’s a Ruby program. First, we print the text, "Enter your name: ", using the print() statement as a prompt and gets to take input. When we run this program, it shows a black screen called the terminal, where we can input values and see the resulting output:

print("Enter your name: ")
name = gets # Taking input by user in variable name
print("Hello #{name} Welcome to Educative\n") # Printing User's name with Hello
Take and display the input of name (variable)

The word, exit, at the end of the output indicates the completion of the program in the terminal.

The code above displays the message, "Hello", before the value of the name variable on the first line. Then, it displays “Welcome to Educative” on the second line.

In the code widget above, when we take input with only the gets statement, it will break the line when used in the print statement. We can use gets.chomp to avoid the line break.

print("Enter your name: ")
name = gets.chomp # Using chomp with the user input to avoid line-break.
print("Hello #{name} Welcome to Educative\n")
Code execution with chomp

The code above displays the output in the same line.

Ruby programming practice

Let’s practice writing the first Ruby program that takes multiple inputs from the user. Keep the following tips in mind.

Tips to write cleaner code:

  • We can add the parentheses () with print.
  • Using "\n" can add a new line in the code.
  • We can use #{} to output variables in print().
  • We can use gets.chomp to avoid the line break.

Tell a story

Let’s write a program that tells a story with the information given by the user. The program should ask the user to enter their name, age, city, college, profession, and pet’s name.

We should also keep in mind that we use the same order of inputs in our code. The program should display the following story, inserting the user’s input into the appropriate locations in the following text:

There once was a person named NAME who lived in CITY. At the age of AGE, NAME went to college at COLLEGE. NAME graduated and went to work as a PROFESSION. Then, NAME adopted an animal named PETNAME. They both lived happily ever after!

# Write your code here
Take and display multiple inputs