Simple Main#

Let create a simple main.go.

mkdir go-package-demo
cd go-package-demo
touch main.go

Update content of main.go and run it.

package main


import "fmt"


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

Let run it.

go run main.go

Simple Module#

Module to manage dependencies such as third party packages. Let create a module

go mod init entest/package-demo

This command will generate a go.mod file which manage dependencies, for example, let use a rsc.io/quote in main.go

package main


import "fmt"
import "rsc.io/quote"


func main() {
	fmt.Println("Hello Hai")
  fmt.Println(quote.Go())
}

To update and download dependencies, let run go mod tidy command.

go mod tidy

Then we can run the main.go as usually.

go run main.go

Simple Package#

By default, we already have main package with main.go. Let create another package called number.

cd go-package-demo
mkdir number
cd number
touch random.go

Let set the update project structure.

|--go-package-demo
   |--number
      |--random.go
   |--go.mod
   |--go.sum
   |--main.go

Content of number/random.go.

package number


func GenerateNumber(n int) []int {
	var result []int
	for i := 1; i <= n; i++ {
		result = append(result, i)
	}
	return result
}

Finally let use the GenerateNumber in the number package for main.go.

package main


import (
	"entest/package-demo/number"
	"fmt"
	"rsc.io/quote"
)


func main() {
	fmt.Println("Hello Hai")
  fmt.Println(quote.Go())
  x := number.GenerateNumber(10)
  fmt.Println(x)
}

Multiple Module#