Golang run times undefined error [resolved]

problem

stay golang There are two files in the same package in , Respectively main.go and server.go,main Function in main.go in , And in main Function refers to server.go A structure in

Run time error ：

PS E:\myworkpace\goworkpace\go_im> go run .\main.go
# command-line-arguments
.\main.go:9:12: undefined: NewServer

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reason

go run： Compile first , The compilation here will only take this main.go Subject to , It leads to the situation that other files referenced cannot be found

go build： Dissimilarity , It will automatically find the reference file and package

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solve

Method 1 ：

go run main.go a.go

Method 2 ：

go run *.go

Method 3 ：

go build

Code case

main.go

package main

import "fmt"

func main() {
    
	fmt.Println("starting")
	server := NewServer("127.0.0.1", 8888)
	server.Start()
}

server.go

package main

import (
	"fmt"
	"net"
)

type Server struct {
    
	Ip   string
	Port int
}

//  Create a server The interface of 
func NewServer(ip string, port int) *Server {
    
	server := &Server{
    
		Ip:   ip,
		Port: port,
	}
	return server
}

func (s *Server) Handler(conn net.Conn) {
    
	//  Currently connected services 
	fmt.Println(" Connection established successfully ！")
}

//  Start the interface of the server 
func (s *Server) Start() {
    
	// socket listen
	listener, err := net.Listen("tcp", fmt.Sprintf("%s:%d", s.Ip, s.Port))
	if err != nil {
    
		fmt.Println("net.Listen err: ", err)
		return
	}
	// close listen socket
	defer listener.Close()

	for {
    
		// accpet
		conn, err := listener.Accept()
		if err != nil {
    
			fmt.Println("listener accept err: ", err)
			continue
		}
		// do handler
		go s.Handler(conn)
	}

}

go.mod

module javapub.net/go_im

go 1.18

Project initialization method ,

go mod init [module]

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