---
title: '#90DaysOfDevOps - Let''s explain the Hello World code - Day 9'
published: false
description: 90DaysOfDevOps - Let's explain the Hello World code
tags: "devops, 90daysofdevops, learning"
cover_image: null
canonical_url: null
id: 1048732
---
## 讓我們解釋一下 Hello World 編碼

### GO程式語言如何運作 

在第 8 天，我們瀏覽了您在工作站上安裝 Go 的過程，然後我們創建了我們第一個 Go的應用程序。 
 
在本章節中，我們將更深入地研究代碼並了解更多關於 Go 程式語言的內容。

### 什麼是編譯？ 
在我們進入第6行Hello World代碼之前[6 lines of the Hello World code](Go/hello.go)，我們必需要對編譯有一點了解。 

像我們常用的Python, Java, Go and C++編程語言都是高階的程試語言。
這意味著它們是人類可辨別的，但是當機器嘗試執行程序時，它需要採用機器可以理解的形式。我們必須將人類可辨別的代碼翻譯成為機器代碼這就稱為編譯。 

![](Images/Day9_Go1.png)

從上面你可以看到我們在第 8 天做了什麼 [Day 8](day08.md)，我們創建了一個簡單的 Hello World main.go檔然後我們使用指令 `go build main.go` 來編譯我們可執行的檔案。 

### 什麼是套件？
套件是在同一目錄中收藏的源碼檔所形成的編譯。我們可以進一步簡化這一點，一個套件是在同一個目錄底下的一堆.go檔案。還記得第 8 天的 Hello 文件檔嗎？如果當您進入更複雜的 Go 程式語言時，您可能會發現你有文件1、文件2、文件3與許多套件所編輯而成的數個.go檔案。 


We use packages so we can reuse other peoples code, we don't have to write everything from scratch. Maybe we are wanting a calculator as part of our program, you could probably find an existing Go Package that contains the mathematical functions that you could import into your code saving you a lot of time and effort in the long run.  

Go encourages you to organise your code in packages so that it is easy to reuse and maintain source code. 

### Hello #90DaysOfDevOps Line by Line 
Now let's take a look at our Hello #90DaysOfDevOps main.go file and walk through the lines. 

![](Images/Day9_Go2.png)

In the first line, you have `package main` which means that this file belongs to a package called main. All .go files need to belong to a package, they should also have `package something` in the opening line. 

A package can be named whatever you wish. We have to call this `main` as this is the starting point of the program that is going to be in this package, this is a rule. (I need to understand more about this rule?)    

![](Images/Day9_Go3.png)

Whenever we want to compile and execute our code we have to tell the machine where the execution needs to start. We do this by writing a function called main. The machine will look for a function called main to find the entry point of the program. 

A function is a block of code that can do some specific task for and can be used across the program. 

You can declare a function with any name using `func` but in this case we need to name it `main` as this is where the code starts. 

![](Images/Day9_Go4.png)

Next we are going to look at line 3 of our code, the import, this basically means you want to bring in another package to your main program. fmt is a standard package being used here provided by Go, this package contains the `Println()`function and because we have imported this we can use this in line 6. There are a number of standard packages you can include in your program and leverage or reuse them in your code saving you the hassle of having to write from scratch. [Go Standard Library](https://pkg.go.dev/std)

![](Images/Day9_Go5.png)

the `Println()` that we have here is a way in which to write to a standard output to the terminal where ever the executuable has been executed succesfully. Feel free to change the message in between the (). 

![](Images/Day9_Go6.png)

### TLDR

- **Line 1** = This file will be in the package called `main` and this needs to be called `main` because includes the entry point of the program. 
- **Line 3** = For us to use the `Println()` we have to import the fmt package to use this on line 6. 
- **Line 5** = The actual starting point, its the `main` function. 
- **Line 6** = This will let us print "Hello #90DaysOfDevOps" on our system. 

## Resources

- [StackOverflow 2021 Developer Survey](https://insights.stackoverflow.com/survey/2021)
- [Why we are choosing Golang to learn](https://www.youtube.com/watch?v=7pLqIIAqZD4&t=9s)
- [Jake Wright - Learn Go in 12 minutes](https://www.youtube.com/watch?v=C8LgvuEBraI&t=312s) 
- [Techworld with Nana - Golang full course - 3 hours 24 mins](https://www.youtube.com/watch?v=yyUHQIec83I) 
- [**NOT FREE** Nigel Poulton Pluralsight - Go Fundamentals - 3 hours 26 mins](https://www.pluralsight.com/courses/go-fundamentals) 
- [FreeCodeCamp -  Learn Go Programming - Golang Tutorial for Beginners](https://www.youtube.com/watch?v=YS4e4q9oBaU&t=1025s) 
- [Hitesh Choudhary - Complete playlist](https://www.youtube.com/playlist?list=PLRAV69dS1uWSR89FRQGZ6q9BR2b44Tr9N) 

See you on [Day 10](day10.md).