Ruby - Conditionals if - else - elsif

Greetings!!!

In this article, we are going to be talking about the control structures inside Ruby. Control structures are really going to provide the action that happens inside of our Ruby programs. It's what's going to decide what takes place under certain circumstances and the first way that we are going to determine those circumstances is using conditionals. So this is, if something is true, we are going to do one thing. If it's not true, do something else.
Right, that's the basic thing. We will run one set of code under one condition, another under different conditions. That's why they are called conditionals. To do that, we are going to use the syntax of conditionals, which is going to be if and then a boolean expression and then end at the end and then in between will be the code that we want to take place if that Boolean value evaluates to true. So if x is equal to 1 then do this bit of code. Otherwise, don't bother, just skip right past it. That's how conditionals will work. Now, we could write two conditionals. We could have if x is equal to 1, then do this.

If x is not equal to 1 then do that. But because that happens so common we have if and else that we can use. So if x is equal to 1, do something, else do the alternative. Right, it allows us just to branch it in two simple directions based on the true/false value of that first conditional. But what if we want in a branch in more than one direction. We don't want to just have a yes or no action. We want to have more complicated choices. Well, we have another option for that which is elsif and that's not a typo. It is e-l-s-i-f and that allows us to do another test before we get to else.

So if x is equal to 1, do something, elsif and let's say x equals to 2, then do something else. But if neither of those is true, then do this default else action. That will be the fallback choice So be careful that you spell elsif correctly. That does trip up a lot of beginners, especially because other programming languages do it differently. So an actual conditional statement might look something like this: if x < 10 puts "Below 10"elsif x > 20 puts "Over 20"else puts "10-20" and then end.

Now notice that we don't have any parenthesis or curly braces or anything like that, letting it know where each of these sections is. Different languages handle that differently and a lot of them require you to put either parenthesis or curly braces. Ruby does not. It's one of the nice things we can just leave them out. The Ruby interpreter knows that when we start a new line, we are ready to start the code in that if statement and it will just keep parsing away until it gets to either elsif, else, or end. And when it gets to one of those, it knows that those are magic keywords that ought to tell it to stop that block of code and now do another part of the conditional.

CHEERS!!!
Maitrey Patel

Comments

Post a Comment

Popular posts from this blog

CRUD Basics

Image
Greetings of the day!!! In this article,   you will see several concepts   which are important for the design of Rails applications.   These concepts will affect the way that we work with URLs,   how we write controller code,   and how our controllers manage our models and database data.   We're gonna start by talking about the concept of CRUD.   Let's begin with reviewing the MVC web architecture diagram.   You must learned how to use controllers and views   to create dynamic pages and return them back to the browser.   Next, learned to interact   with the database by creating models and associations. MVC Architecture And worked with those, not from a browser,   but via the Rails console would be feasible.   Now, we need to put the two together   and learn how to work with the models   inside our controllers.   Then we'll be able to manipulate   our database data from the browser,   in the same way that we did from the console.   The way that we're
Read more

Installing MySQL with Ruby on Rails

Installing MySQL with Ruby on Rails Our web application uses a database to store information. In this blog, I'm going to show you how to get the MySQL database installed with Ruby on Rails. If you already have it installed either because you've already been developing with it, or because you've taken another training course which included it, then you won't need to install it again. Just skim over this page to make sure that you know everything I cover. If you prefer to use a different database such as SQLite or PostgreS, you can, and without making many changes to what I'm going to show you. But we're going to be sticking with MySQL for this blog. One other note, some Windows users already use Microsoft Access as a database and wonder if they can use that with Rails. Access isn't really robust enough for web server usage. It's not supported on Rails, and there's no official database adapter to make it work. There are some unofficial adapters an
Read more

How to solve migration issues with rails

Greetings friends!!! Migrations make managing your database schema easy, however, problems often occur when we're running our migrations and run into a bug in our migration code. It can leave your migrations in a broken state where you can't migrate up and you can't migrate down. It's important to learn how this happens and how to resolve these problems when they occur. Use rails db:migrate version 0  to migrate to 0 level. STEPS to recover migrations issue: Make a note of migration issue. Try to resolve it manually by changing migration file. Perform migration to version 0. This will rollback all migrations. Comment all above code inside migration having an issue. Let's say for example if your line # 5 is causing an issue comment your code till line #4. Run rails db:migrate again  Verify that it shows success and double check with the database too, If it showing migration error perform step 1 to 5 till it shows the success. Uncomment your code and yo
Read more