The Classic Hello World Program in GO

Introduction

To write your first code in any programming language, it has become a norm to start with a simple hello world program. In this post, I will be showing how to write a program in GO and explain all the parts of the program. Lets begin!👍🏼

Program

The first step is creating a helloworld folder in your $GOPATH. To learn more about how to do this, view my previous article here.

In the main.go file, write the following piece of code:

package main

import "fmt"

func main() {
   fmt.Println("Hello World!")
}

Explanation

package main should always be first statement in a GO program. This creates an executable GO program. Every GO file can only belong to a single package.
main represents the name of the package which this file belongs to.
import: The import keyword is used to import reusable pieces of code from other packages to use in our program.
import fmt: This line imports the fmt package. fmt is a package that ships with the GO standard library and is used for formatted I/O.
func main is an entry point to this program. It is a special function which tells GO where to start execution. In all executable programs, almost everything will be run under this function.
func represents a function. A function contains a block of code that can be executed when the function is called. It is used for reusable code.
fmt.Println: This line prints "Hello World" to the terminal when the program is run. Println is a method of the fmt package that writes to the standard output.

Running the Program

There are two(2) tools available to run a GO program.

go build: this command compiles the GO program and we can then run afterwards. First we compile the program using:
```
$ go build
```
It seems as though nothing happened but in the background, this compiles the GO code to machine code. We need to use the ls command to see the executable file. And then we run it by typing ./helloworld.

This way of running GO programs is best suited for deployment.
go run: this command both compiles and run the GO program.
```
$ go run main.go
```
This is the most suitable for prototyping i.e. when developing

Conclusion

That is all when trying to write and run your first program in GO. With this, we should be able to:

understand the basic parts of a GO program.
what statements like the package main and import clause does.
how to print to the console.
how to run a GO program.