具有联合声明/赋值运算符的全局变量内联赋值和另一个未声明的变量丢失范围？

问题描述：

This Go program will not compile. It throws the error global_var declared and not used

package main

import "log"

var global_var int

func main() {

    global_var, new_string := returnTwoVars()

    log.Println("new_string: " + new_string)
}

func returnTwoVars() (int, string) {
    return 1234, "woohoo"
}

func usesGlobalVar() int {
    return global_var * 2
}

However, when I remove the need for using the := operator by declaring new_string in the main function and simply using =, the compiler doesn't have a problem with seeing that global_var is declared globally and being used elsewhere in the program. My intuition tells me that it should know that global_var is declared already

此Go程序将无法编译。它将引发错误global_var声明且未使用 code> p>

 包main 
 
import“ log” 
 
var global_var int 
 
func main  （）{
 
 global_var，new_string：= returnTwoVars（）
 
 log.Println（“ new_string：” + new_string）
} 
 
func returnTwoVars（）（int，string）{
返回1234  ，“ woohoo” 
} 
 
func使用GlobalVar（）int {
返回global_var * 2 
} 
  code>  pre> 
 
 但是，当我删除 通过在主函数中声明 new_string  code>并使用：=  code>运算符，而仅使用 =  code>，编译器就不会发现 global_var  code>是全局声明的，并在程序的其他位置使用。 我的直觉告诉我应该知道 global_var  code>已经声明 p> 
  div>

答

The compiler doesn't complain about the global_var outside main. It only complains about the newly created global_var in main that you don't use. Which you can check by looking at the line number that go mentions.

You can try an empty program with a global_var outside any function that nobody references: no problems there. And of course, the usesGlobalVar function that does reference the actual global symbol has nothing to do with the one you create in main.

具有联合声明/赋值运算符的全局变量内联赋值和另一个未声明的变量丢失范围？

相关推荐