Joel Bryan Juliano - From Ruby to Golang : A Ruby Programmers Guide to Learning Go

Everything needs communication. Animals and humans communicate using physical gestures and sounds. Most insects have special antenna in them that they use to communicate to other insects, or emits a sounds or a scents that allows it to exchange information to other animals. Plants also have a special way to communicate to other plants through electric signalling or using others hosts to send their message.

From gigantic animals to small microscopic bacterias, viruses to cells, all have a special way to exchange message, they all have a way to coordinate information with each other.

Computers and software also requires a lot of communication.

Inside the computer hardware, electrical signals are sent to each individual components where they are task to perform a very specific function. And computers itself communicate to other computers via wire, wireless and The Internet.

It is hard to image a world without communication!

In programming, there are also various levels of ways to communicate to your code. In this chapter, we will discuss ways we can communicate to individual parts of code, one of them is variables.

If you need to pass, exchange and coordinate values that are bound to specific parts of the code, then we can use a variable.

Variables can either be a local variable that you can only access from inside the function, or global variable that you can globally access throughout your code.

For our first program example, we will create a function that takes a single word input, then output the word Hello World.

Here is an example of a local variable in Ruby. In this example, we declared a local variable hello inside a function say_hello.

And when we run the Ruby code, it will output Hello World.

However, if we want to change the hello variable to store a different message, we cannot directly change it from outside the function.

So even though we change the hello variable, this will still output a Hello World.

1. What have we learned?
We learned that we can use a local variable to store a value that we can only access from inside the function.