如何在Go中定义和调用函数

介绍 (Introduction)

A function is a section of code that, once defined, can be reused. Functions are used to make your code easier to understand by breaking it into small, understandable tasks that can be used more than once throughout your program.

函数是一段代码，一旦定义，便可以重用。 通过将函数分解为可理解的细小任务，这些函数可在整个程序中多次使用，这些函数使代码更易于理解。

Go ships with a powerful standard library that has many predefined functions. Ones that you are probably already familiar with from the fmt package are:

Go附带了功能强大的标准库，该库具有许多预定义功能。 您可能已经从fmt包中熟悉的是：

• fmt.Println() which will print objects to standard out (most likely your terminal).

  fmt.Println()会将对象打印为标准输出(很可能是您的终端)。

• fmt.Printf() which will allow you to format your printed output.

  fmt.Printf()它将允许您格式化打印输出。

Function names include parentheses and may include parameters.

函数名称包含括号，并且可以包含参数。

In this tutorial, we’ll go over how to define your own functions to use in your coding projects.

在本教程中，我们将介绍如何定义自己的函数以在编码项目中使用。

定义功能 (Defining a Function)

Let’s start with turning the classic “Hello, World!” program into a function.

让我们从经典的“ Hello，World！”开始 程序变成一个函数。

We’ll create a new text file in our text editor of choice, and call the program hello.go. Then, we’ll define the function.

我们将在所选的文本编辑器中创建一个新的文本文件，然后调用程序hello.go 。 然后，我们将定义函数。

A function is defined by using the func keyword. This is then followed by a name of your choosing and a set of parentheses that hold any parameters the function will take (they can be empty). The lines of function code are enclosed in curly brackets {}.

通过使用func关键字定义func 。 然后是您选择的名称和一组括号，这些括号包含函数将采用的所有参数(它们可以为空)。 功能代码行括在大括号{} 。

In this case, we’ll define a function named hello():

在这种情况下，我们将定义一个名为hello()的函数：

func hello() {}

This sets up the initial statement for creating a function.

这将建立用于创建函数的初始语句。

From here, we’ll add a second line to provide the instructions for what the function does. In this case, we’ll be printing Hello, World! to the console:

从这里开始，我们将添加第二行以提供有关该功能的说明。 在这种情况下，我们将打印Hello, World! 到控制台：

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

Our function is now fully defined, but if we run the program at this point, nothing will happen since we didn’t call the function.

现在已经完全定义了函数，但是如果此时运行程序，则由于未调用函数，因此不会发生任何事情。

So, inside of our main() function block, let’s call the function with hello():

因此，在我们的main()函数块中，让我们使用hello()调用该函数：

package main

import "fmt"

func main() {
    hello()
}

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

Now, let’s run the program:

现在，让我们运行程序：

You’ll receive the following output:

您将收到以下输出：

   
   
   

    
    
    Output
   
   
   
Hello, World!

Notice that we also introduced a function called main(). The main() function is a special function that tells the compiler that this is where the program should start. For any program that you want to be executable (a program that can be run from the command line), you will need a main() function. The