Unable to include multi file in the golang

I know this question has been asked before and I've tried all possible answers, but nothing still didn't help me.

However to refresh the question again and to elaborate my problem. I'm actually trying to include a simple file to the main.go file. My folder structure and the rest of the information as follows:

\src\
   Multi-file\
     lib\Car.go
   main.go

Car.go

 package main
    
    type Car struct {
        numberOfDoors int
        cylinders int
    }

main.go

package main 

import (
    "fmt"
)

func main() {
    c := Car{4,6}
    fmt.Println(c)
}

When I complie the main.go I'm getting the following error

# command-line-arguments
.\main.go:8: undefined: Car

Here is my go env details:

set GOARCH=amd64
set GOBIN=
set GOEXE=.exe
set GOHOSTARCH=amd64
set GOHOSTOS=windows
set GOOS=windows
set GOPATH=C:\xampp\htdocs\golang
set GORACE=
set GOROOT=C:\Go
set GOTOOLDIR=C:\Go\pkg\tool\windows_amd64
set GO15VENDOREXPERIMENT=
set CC=gcc
set GOGCCFLAGS=-m64 -mthreads -fmessage-length=0
set CXX=g++
set CGO_ENABLED=1

FYI: I tried including as package also that didn't even help me out.

Any help would be extremely appreciated.

Set up your workspace for programs and libraries by following the instructions: How to Write Go Code.

For your example, a two file main package,

src/car
├── car.go
└── main.go

$ cd src/car
$ go run main.go car.go
{4 6}
$ go build car && ./car
{4 6}
$ go install car && car
{4 6}
$ 

main.go:

package main

import (
	"fmt"
)

func main() {
	c := Car{4, 6}
	fmt.Println(c)
}

car.go:

package main

type Car struct {
	numberOfDoors int
	cylinders     int
}

You should not have 2 files, that are declared in the same package but are not residing in the same directory. One solution could be to have this directory structure instead:

src\
  car\
    car.go
  main.go

car.go

package car

type Car struct {
    NumberOfDoors int
    Cylinders     int
}

main.go

package main

import (
    "car"
    "fmt"
)

func main() {
    c := car.Car{4, 6}
    fmt.Println(c)
}

Of course, Car structure not being in main package, I had to:

• change to uppercase the first letter of NumberOfDoors and Cylinders fields from car.Car struct, so that they can be accessed from main package
• replace the call to Car{4,6} with car.Car{4,6}
• code in car.go is not part of package main anymore, you can view it as a car library now. That's why the Car struct is now declared being part of package car

Like that, you can build and run in one step with:

go run main.go