hello

./code/hello2/ex.go

package main

import "fmt"

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

To run the program, use:

go run ex.go

For a recent version of go, go build will throw the following error:

$ go build
go: cannot find main module, but found .git/config in /Users/fangjun/open-source/notes
        to create a module there, run:
        cd ../../../../.. && go mod init

But we can use go build ex.go, which works fine and will generate an executable ex.

To format the file in-place, use go fmt ex.go.

To see the help for a command, for instance the command for go fmt, use go help fmt.

To view the doc, run:

gofmt
# The above command is equivalent to
gofmt -http localhost:6060
# Then start your browser and visit http://localhost:6060

To install a tour of goo, run

# see https://go.dev/tour/list
go install golang.org/x/website/tour@latest

import "fmt"
import "math/rand"

is equivalent to

import (
  "fmt"
  "math/rand"
)

Format specifier:

• %v, for any value

• %T, print the type

• %x, same as C/C++

• %s, for string and byte slice

# to view the help information of the function fmt.Printf
go doc fmt.Printf

go doc builtin.append
go doc builtin.make
go doc builtin.copy
go doc builtin.new
go doc builtin.len
go doc builtin.cap