gopl

go get -v golang.org/x/tools/cmd/goimports   // timeout
1149 # 启用 Go Modules 功能
1150 export GO111MODULE=on
1151 # 配置 GOPROXY 环境变量
export GO111MODULE=on
export GOPROXY=https://goproxy.io

// go option test
推荐：blog: Go工具和调试详解

// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
// License: https://creativecommons.org/licenses/by-nc-sa/4.0/

// See page 1.

// Helloworld is our first Go program.
//!+
package main

import "fmt"

var len = 10
var (
    n1 = 1
    n2 = 2
)
func main() {
    fmt.Println("Hello, 世界")
    // single var
    var i int
    // i = 1.1 // constant 1.1 truncated to integer go 
    fmt.Println("i =", i)
    var j = 10
    fmt.Println("j =", j)
    k := 10
    fmt.Println("k =", k)

    // multi var
    var n1, n2, n3 int
    fmt.Println("n1 =", n1, "n2 =", n2, "n3 =", n3)
    m1, m2, m3 := 100, "tom", 999
    fmt.Println("m1 =", m1, "m2 =", m2, "m3 =", m3)

    var len = 20
    fmt.Println("len =", len)
    fmt.Printf("len`s type is %T", len)  // show type
}

//!-