哪个公司？报一下别让后来的同学掉坑里。

@cjpjxjx 台湾工资二十年不涨了。。

这个版本很垃圾不要用，如果非要用 Ubuntu 换 16.04

@Linxing 老哥怎么实现

顺手给你加个引用"The distinction between a declaration and a definition may seem obscure at this
point but is actually important. To use a variable in more than one file requires
declarations that are separate from the variable ’ s definition. To use the same variable
in multiple files, we must define that variable in one — and only one — file. Other files
that use that variable must declare — but not define — that variable."

example:
"extern double pi = 3.1416; // definition"

详见<C++ Primer 5th> "2.2.2. Variable Declarations and Definitions"