Video source ：B standing 《golang Introduction to project practice [2021 newest Go Language course , There is no nonsense , Dry only ！ Ongoing update ...]》

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Attach summary sticker ：Go Language self-study series | Summary _COCOgsta The blog of -CSDN Blog

golang There is a special function init function , Precede main Function execution , Implement some initialization operations at the package level .

init The main characteristics of function

• init Function precedes main Function automatic execution , Cannot be called by other functions
• init Function has no input parameters 、 Return value
• Each bag can have more than one init function
• Each source file of a package can also have multiple init function , This is special
• Of the same package init Execution order ,golang There is no clear definition , When programming, be careful that the program does not rely on this execution order
• Different packages init The function determines the execution order according to the dependency of package import

golang Initialization sequence

Initialization sequence ： Variable initialization ->init()->main()

example

package main

import "fmt"

var i int = initVar()

func init() {
    fmt.Println("init2")
}

func init() {
    fmt.Println("init...")
}

func initVar() int {
    fmt.Println("initVar...")
    return 100
}

func main() {
    fmt.Println("main....")
}

Running results

[Running] go run "d:\SynologyDrive\ software development \go\golang Introduction to project practice \goproject\360duote.com\pro01\test.go"
initVar...
init2
init...
main....