How to import packages in go language

In the Go language, you can use the import keyword to import packages. The imported package name must be surrounded by double quotes. The package name is the path calculated starting from GOPATH, and uses "/" to separate the paths. There are two basic formats for importing packages in the go language: 1. Single-line import, with the syntax "import "package name""; 2. Multi-line import, with the syntax "import("package name 1" "package name 2" ...)".

The operating environment of this tutorial: Windows 7 system, GO version 1.18, Dell G3 computer.

Go language import import package - use other code in the code

Can be placed after a Go language source file package declaration statement and before other non-import declaration statements , containing zero to more import package declaration statements. Each import statement can specify an import path individually, or multiple import paths can be imported simultaneously through parentheses. To reference identifiers of other packages, you can use the import keyword. The imported package name is surrounded by double quotes. The package name is the path calculated starting from GOPATH and is separated by /.

Default import writing method

There are two basic formats for import, namely single-line import and multi-line import. The import codes of the two import methods The effect is consistent.

1) Single-line import

The single-line import format is as follows:

import "包1"
import "包2"

2) Multi-line import

When importing multiple lines, the package name is in the import The order does not affect the import effect. [Related recommendations: Go video tutorial, Programming teaching]

The format is as follows:

import(
    "包1"
    "包2"
    …
)

Import package case

1. Single-line import of Go language package

Use the import keyword to import Go language package in one line

package main
//使用 import 关键字，单行导入 Go 语言包
import "fmt"
import "strconv"
func main() {
var strNum = "100"
if num, err := strconv.Atoi(strNum); err != nil{
fmt.Println("Convert err, Err =", err)
}else{
fmt.Println("Convert ok, Num =", num)
}
}

After the program is run, the console output is as follows:

First, we use the package keyword to define the package where the file is located as the main package, and then use import to import the Go language package in a single line, importing the fmt package and strconv package.

Finally, in the main function, we define a string type variable strNum, and call the Atoi function in the strconv package to convert the string strNum into an int type num. At the same time, the function returns a The return value of the error interface type.

We determine whether the conversion is successful by judging whether the second parameter of the function is nil. If not, we print an error message. Otherwise, print the converted result.

2. Multi-line import of Go language package

Use the import keyword to import Go language package in multiple lines

package main
//使用 import 关键字，多行导入 Go 语言包
import (
	"fmt"
	"strconv"
)
func main() {
	var strNum = "100"
	if num, err := strconv.Atoi(strNum); err != nil{
		fmt.Println("Convert err, Err =", err)
	}else{
		fmt.Println("Convert ok, Num =", num)
	}
}

First, we use the package keyword to define the package where the file is located as the main package, and then use import multi-line to import the Go language package, importing the fmt package and strconv package respectively.

Finally, in the main function, we call the Println function of the fmt package and the Atoi function in the strconv package.

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