Variables are used in order to name a value of some sort to reference later.
name = "Bob"
puts "Hello #{name}"
Here we store the value "Bob" in the variable name in order to be referenced in our puts line.
Interpolation is where we take a ruby expression and get the value of that expression to inject in a ruby string.
name = "Bob"
puts "Hello #{name}"
Here when we interpolate the name variable, we are using ruby to run name which gives us back "Bob" and injects "Bob" into the puts statement.
Integers are numbers in code. We use integers to do math.
1 + 1 # gives us 2
Booleans are true or false values. True and false are used in code in order to determine flow.
if true
puts "This statement is true"
else
puts "This won't even read because it stopped at the if"
end
So here we use a boolean to tell the code what to print out.
Pro Tip Booeans are not the same as truthy and falsey, which work a lot like true and false, however can have values such as integers, strings, etc. Only nil or false is falsy in Ruby, everything else is truthy. Booleans are just more to the point of yes or no.
Where variables are used to store values, methods are used to run a block of logic and print or send back (return) some sort of information to be used in the code.
# defining a method
def greeting
puts "Hello World!"
end
# callings or using our method
greeting
When a method needs a value from an external source. The only way we can pass it information is via an argument. For example:
def say_hello_to(name)
puts "Hi #{name}!"
end
say_hello_to("Bob") # prints Hi Bob!
say_hello_to("Sarah") # prints Hi Sarah!
In this example we create a method that takes in 1 argument of name. We don't know who's name that might be, however we will assume it will be a name that is a string. Then we'll take that name and inject it into our puts statement. Therefor when we call it
with say_hello_to("Bob"). We print out "Hi Bob!", we can use that same method over and over again as long as we pass in names. Arguments allows us the ability for our logic to change based on what we pass in.
Default arguments give us the option to pass in an argument, or let it fall back to a default value. For example:
def say_hello_to(name="Ruby Programmer")
puts "Hello #{name}!"
end
say_hello_to # prints out Hello Ruby Programmer!
say_hello_to("Bob") # prints out Hello Bob!
By not passing in an argument in the first call, it defaults to the string we set that argument to. However when we pass in an argument to the method, it will override the default value and the value we passed in becomes the value of the argument.