Variables

Think of variables as a tracker of values. Typically, we say that we create a variable and we assign a value to that variable. We also often can say that we intialize a variable with a value if we want to be specific and say that memory is allocated to a variable and it will automatically keep track of a specific value.

To use a variable, you have to make sure it is declared (and most likely defined in the same process).

Prerequisites

If you didn’t understand the paragraph above then, do some searches to understand the vocabulary. Most likely however, you haven’t read the previous two concepts:

• Values
• Data Types

Modifiers

Variables in many programming languages can be created differently by being modified.

Scope

Different kinds of variables can be created. In both dynamically-typed and statically-typed languages, there’s often a way to make a variable global or local to a specific kind of scope.

Dynamically-typed vs. Statically-typed

Dynamically-typed languages figure out what type of data your variable hold automatically while statically-typed languages require you to specify what the type is.

Variables referring to an integer in some different programming languages.

my_number = 10

def hello():
    global my_number
    # global operator makes
    # variable global.
    my_number = 20

hello()
print(my_number) # We expect 20 now

-- Outside of any scope (function, loops, if-statements...)
myNumber = 10

function foo()
    local myLocal = 20
end

print(myNumber) -- Legal
print(myLocal) -- Gives nil. Not what we intended

// block-scoped
if (true) {
    let myNumber = 1
}

console.log(myNumber) // will error

// function-scope
function bar() {
    if (true) {
        var hey = 10
    }
    print(hey) // does not error because of var
}