In go, how do I make global variables

huangapple go评论88阅读模式
英文:

In go, how do I make global variables

问题

包 main

import (
"fmt"
"bufio"
"os"
)

var inputX, inputY string

func main() {
fmt.Print("LOADED!\n")
fmt.Print("在这里插入 y 的值:")
scanner := bufio.NewScanner(os.Stdin)
scanner.Scan()
inputY = scanner.Text()
inputXfunc()
}

func inputXfunc() {
fmt.Print("在这里插入 x 的值:")
scanner := bufio.NewScanner(os.Stdin)
scanner.Scan()
inputX = scanner.Text()
slope()
}

func slope() {
fmt.Println(inputY / inputX)
}

每当我运行这个程序时,它会显示 inputX 和 inputY 未定义。我该如何使该程序使用在所有函数中都可访问的变量?我只想做的是将 inputY 除以 inputX,然后打印出结果。

英文:
package main 

import (
	"fmt"
	"bufio"
    "os"
)

func main() {
	fmt.Print("LOADED!\n")
    fmt.Print("insert y value here: ")
    inputY := bufio.NewScanner(os.Stdin)
    inputY.Scan()
    inputXfunc()
}

func inputXfunc() {
    fmt.Print("insert x value here: ")
    inputX := bufio.NewScanner(os.Stdin)
    inputX.Scan()
    slope()
}

func slope() {
    fmt.Println(inputX.Text())
}

Whenever I run this program, it says, that inputX and inputY are unidentified. How do I make this program use variables that are accessible to all of the functions? All I want to do is devide inputY by inputX then print out the result

答案1

得分: 7

我只是将我的评论作为答案...不过我建议不要这样做,你可以在包范围内声明变量。代码如下:

package main

import (
    "fmt"
    "bufio"
    "os"
)

var inputX io.Scanner

func main() {
    fmt.Print("LOADED!\n")
    fmt.Print("insert y value here: ")
    inputY := bufio.NewScanner(os.Stdin)
    inputY.Scan()
    inputXfunc()
}

func inputXfunc() {
    fmt.Print("insert x value here: ")
    inputX = bufio.NewScanner(os.Stdin) // 在这里去掉赋值初始化的简写
    inputX.Scan()
    slope()
}

func slope() {
    fmt.Println(inputX.Text())
}

然而,更好的选择是将你的方法定义更改为接受参数,并根据需要将值传递给它们。代码如下:

func slope(inputX bufio.Scanner) {
    fmt.Println(inputX.Text())
}

slope(myInputWhichIsOfTypeIOScanner)
英文:

I'm just putting my comment as an answer... I would recommend against this however you could just declare the variable at package scope. It would look like this;

package main 

import (
    "fmt"
    "bufio"
    "os"
)

var inputX io.Scanner

func main() {
    fmt.Print("LOADED!\n")
    fmt.Print("insert y value here: ")
    inputY := bufio.NewScanner(os.Stdin)
    inputY.Scan()
    inputXfunc()
}

func inputXfunc() {
    fmt.Print("insert x value here: ")
    inputX = bufio.NewScanner(os.Stdin) // get rid of assignment initilize short hand here
    inputX.Scan()
    slope()
}

func slope() {
    fmt.Println(inputX.Text())
}

However a better choice would be to change your method definitions to accept arguments and pass the values into them as needed. This would like like so;

func slope(inputX bufio.Scanner) {
        fmt.Println(inputX.Text())
    }

 slope(myInputWhichIsOfTypeIOScanner)

答案2

得分: 3

你可以创建一个init()函数,并在main.go中使用godotenv等包来设置操作系统的环境变量:

global.go文件

package global

import (
	"log"
	"os"
	"strconv"

	"github.com/joho/godotenv"
)

var (
	SERVER_HOST string
	SERVER_PORT int
)

func InitConfig() {

	err := godotenv.Load()
	if err != nil {
		log.Fatal("Error loading .env file")
	}

	SERVER_HOST = os.Getenv("SERVER_HOST")
	SERVER_PORT, _ = strconv.Atoi(os.Getenv("SERVER_PORT"))
}

main.go文件

package main

import (
	G "path/to/config"
)

func init() {
	G.InitConfig()
}

func main() {
	G.Init()
}

你仍然需要在其他包中导入G包来使用这些变量,但我认为处理Go(或任何其他语言)中的全局变量的最佳方法是利用环境变量。

英文:

You can create an init() function and make use of it in the main.go by using package like godotenv to set os's environment variables:

global.go file

package global

import (
	"log"
	"os"
	"strconv"

	"github.com/joho/godotenv"
)

var (
	SERVER_HOST        string
	SERVER_PORT        int
)

func InitConfig() {

	err := godotenv.Load()
	if err != nil {
		log.Fatal("Error loading .env file")
	}

	SERVER_HOST = os.Getenv("SERVER_HOST")
	SERVER_PORT, _ = strconv.Atoi(os.Getenv("SERVER_PORT"))
}

main.go file

package main

import(
    G "path/to/config"
)

func init() {
    G.InitConfig()
}

func main() {
    G.Init()
}

You will still have to import "G" package in other packages to use the variables, but I think the best way to tackle global variables in Go (or any other languages) is to make use of environment variables.

huangapple
  • 本文由 发表于 2015年11月25日 07:55:29
  • 转载请务必保留本文链接:https://go.coder-hub.com/33906141.html
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