A beginners guide to Ruby, Part 3

Inori · 04-01-2015, 01:46 PM

Nightc||ed's Beginner Ruby Guide

if/else and case classes:

In every language, there's some type of if/else statement. Even in batch.
if/else statements in Ruby are structured like so:

Code:
if <variable> = <condition>
    <do this>
elsif <variable> = <some other condition> #not needed but usually used. Can have as many as you want
    <do this>
else #if the variable is anything else
    <do this>
end #ends the statement

As mentioned, you can have as many elsif statements as you want, but they get a little confusing after a while. That's why I prefer case classes for more complex conditionals.
The case class is structured similar to if/else but a little more abstract.

Code:
case <variable>
    when <condition>
        <do this>
    when <other condition>
        <do this>
end

Again, you can have as many whens as you'd like and you MUST use end to finish your class.

Math:

Math in Ruby is pretty simple, but extremely useful.
the operators are as follows:

Code:
+ #addition
- #subtraction
* #multiplication
/ #division
% #modulus (divides and returns remainder)
** #exponent

There are also some special methods for advanced math:

Code:
Math.sqrt(<value or set variable>) #square root
Math::PI #pi to 15 digits
Math::E #e to 15 digits

and finally, my least favorite, trig:

Code:
Math::sin(<value or set variable>)
Math::cos(<value or set variable>)
Math::tan(<value or set variable>)

For the methods involving advanced math and trig, you MUST capitalize Math. I cannot stress this enough.

Loops:

Spam time! Ruby, being as redundant as it is, has several ways to make loops. A few more common ones are while, .times and .each.
I'll explain how each of them work:

while:

Pretty simple. While the specified value is in the range of whatever condition you set, the code inside the statement will loop.
For an example: a simple counting program

Code:
i = 0
while i > 10
    puts i
    i += 1
end

The += is a shorter version of i = i + 1

.times:

.times is what it sounds like; the number of times specified, it will iterate over the contained code.

Code:
i = 0
<value>.times do
    puts i
    i += 1
end

.each:

.each is used for arrays, ranges and Hashes, which we'll cover next time.
.each works as follows:

Code:
a = *(1..10) #I'm using a splat range because I'm lazy, I'll explain this next part.
a.each do |num| #the |num| is for each value in the array
    num *= 2
end

since num is a variable while inside the .each class, you can treat it like one.

Thanks for reading, guys! I seem to be getting some positive feedback so I'll continue these for a while.
-Nightc||ed