Daily Exercise 004: Go-Golang-Tutorial-2-Your-First-Go-File

Day 1 Script

Let's start by creating our first simple Go file. We will call it main dot go, because that is a common name for the main application file. Every Go file you create must be part of a package, which is basically a collection of files and code. In our case, we will use package main at the start of the file. This tells the Go compiler that our code should be compiled into an executable program at the end. If we choose to build the application, Go will create a standalone executable file for us. Running that file will start our program automatically. If you were making a shared library instead, you would name your package something else to describe that library. Since we are making a program to run on our computer, we will always use package main for the entry file.

Day 1 Translate

Day 2 Script

Next, we'll talk about the main function declaration. All functions in Go start with the func keyword. The name of this function is very important because it serves as the entry point of our application. When we run our program, Go looks through the files to find this specific function and executes it first. If you named it something else, Go would not fire it automatically when the program starts. It is also important to remember that there must be only one main function in the entire application. You do not need to have one in every single file within your package. You just have one main function in your entry file. In other files, you can create different functions and call them from inside this main function, but the entry point remains unique.

Day 2 Translate

Day 3 Script

Now we will look at how to import packages. We use the import keyword followed by the package name, such as fmt. This package is part of the Go standard library, which contains many useful tools for different tasks. The fmt package is specifically used for formatting strings and printing messages to the console. It contains several methods, and you might notice that they all start with a capital letter. This is because in Go, you must use a capital letter to export a function or method from a package. For example, we use the print line method to display text. We will learn more about formatting and printing later, but for now, just remember that we access these methods by typing the package name followed by a dot and the method name.

Day 3 Translate

Day 4 Script

To run your Go program, you need to open a terminal and make sure you are in the correct directory. You can use a keyboard shortcut or the menu to open a new terminal window. Once you have verified your location, you can type go run followed by the name of your file, which is main dot go. When you hit enter, Go will automatically find and execute the main function we discussed earlier. You should see your message printed directly to the console. This simple command is a very quick way to test your code during development. It compiles and runs the program in one step, so you can see the results immediately. This process allows us to verify that everything is working correctly before we move on to more complex features like variables.

Day 4 Translate

Day 5 Script

Variables are used to store information like strings and numbers. There are several ways to declare them in Go. The first way is to use the var keyword, followed by the variable name and its type. For example, you can declare a name as a string and set it equal to a value in double quotes. Go also allows you to omit the type, and it will infer it automatically based on the value you provide. Another very common shorthand is to use the colon equals operator, which initializes the variable without the var keyword. This is the method we will use most often inside functions. However, keep in mind that this shorthand cannot be used outside of a function. Whether you use explicit typing or inference, Go ensures that your variables maintain their type throughout the program.

Day 5 Translate