How to import packages in go language

Methods for importing packages in Go language: 1. Import package files through the import command; 2. Import packages through point operations; 3. Import packages using alias operations; 4. Through "_" operations way to import the package.

Environment of this article: Windows 7 system, Go1.11.2 version, this article is applicable to all brands of computers.

Recommended: "Go Language Tutorial"

Several Ways to Import Packages in Go (import)

1: General syntax for package import

The import command is often used when writing Go code to import package files. The way to see it is as follows:

   import(
       "fmt"
   )
  //然后在代码里面可以通过如下的方式调用
  fmt.Println("hello world")

The above fmt is the standard library of Go language. It actually goes to GOROOT to load the module. Of course, Go's import also supports the following two ways to load modules written by yourself:

  //相对路径     
  import   "./test_model"  //当前文件同一目录的test_model目录，但是不建议这种方式import
 
  //绝对路径    
  import   "mygoproject/test_model"  //加载GOPATH/src/mygoproject/test_model模块

2: Other ways to import packages

2. 1 point operation

Sometimes you will see the following way to import a package

import . “fmt”

The meaning of this point operation is that after the package is imported, when you call the function of this package , you can omit the prefix of the package name, which is the

  fmt.Println(“hello world”)  
  //可以省略的写成
  Println(“hello world”)

2.2 Alias ​​operation

As the name suggests, you can name the package to another name that is easy to remember

  import( f “fmt” )   
  //别名操作调用包函数时前缀变成了重命名的前缀，即
  f.Println(“hello world”)

2.3 _ Operation

import (
      "database/sql"
      "fmt"
      _ "github.com/go-sql-driver/mysql"
      "time"
  )  
   //_操作其实只是引入该包。当导入一个包时，它所有的init()函数就会被执行，但有些时候并非真的需要使用这些包，仅仅是希望它的init()函数被执 行而已。这个时候就可以使用_操作引用该包了。即使用_操作引用包是无法通过包名来调用包中的导出函数，而是只是为了简单的调用其init函数()。

For more related technical articles, please visit the golang tutorial column!

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