是静态类变量与extern变量相同，只有类范围？ [英] Are static class variables the same as extern variables, only with class scope?

问题描述

在我看来，静态类变量与extern变量完全相同，因为您只需在 static int x / 中声明< extern int x 语句，实际上在其他地方定义（通常在.cpp文件中）

It seems to me that a static class variable is identical to an extern variable, because you only declare it in the static int x / extern int x statement, and actually define it elsewhere (usually in a .cpp file)

// .h file
class Foo
{
    static int x ;
} ;

// .cpp file
int MyClass::x = 0 ;

外部变量：

Extern variables:

// .h file
extern int y;

// .cpp file
int y = 1;

在这两种情况下，变量都被声明一次，并在一个文件中定义，

In both cases the variable is declared once somewhere, and defined in a file that will not be included more than once in the compilation (else linker error)

推荐答案

是的，都有静态存储持续时间和外部链接;它们本质上具有相同的运行时属性，只有（编译时）可见性不同。

Yes, both have static storage duration and external linkage; they have essentially the same run-time properties, only differing in (compile-time) visiblity.

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