`static const` 与 `const` 的 C++ 语义
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C++ semantics of `static const` vs `const`
提问by Clifford
In C++ specifically, what are the semantic differences between for example:
具体在 C++ 中，例如之间的语义差异是什么：
static const int x = 0 ;
and
和
const int x = 0 ;
for both staticas a linkage and a storage class specifier (i.e. inside and outside a function).
两者static作为键和存储类说明（即内部和外部的函数）。
采纳答案by Ben Voigt
At file scope, no difference in C++. constmakes internal linkage the default, and all global variables have static lifetime. But the first variant has the same behavior in C, so that may be a good reason to use it.
在文件范围内，C++ 没有区别。 const使内部链接成为默认值，并且所有全局变量都有静态生命周期。但是第一个变体在 C 中具有相同的行为，因此这可能是使用它的一个很好的理由。
Within a function, the second version can be computed from parameters. In C or C++ it doesn't have to be a compile-time constant like some other languages require.
在一个函数中，第二个版本可以从参数中计算出来。在 C 或 C++ 中，它不必像其他一些语言所要求的那样是编译时常量。
Within a class, basically the same thing as for functions. An instance constvalue can be computed in the ctor-initializer-list. A static constis set during startup initialization and remains unchanged for the rest of the program. (Note: the code for staticmembers looks a little different because declaration and initialization are separated.)
在一个类中，基本上与函数相同。const可以在ctor-initializer-list 中计算实例值。Astatic const在启动初始化期间设置，并在程序的其余部分保持不变。（注意：static成员的代码看起来有点不同，因为声明和初始化是分开的。）
Remember, in C++, constmeans read-only, not constant. If you have a pointer-to-constthen other parts of the program may change the value while you're not looking. If the variable was defined with const, then no one can change it after initialization but initialization can still be arbitrarily complex.
请记住，在 C++ 中，const表示read-only，而不是constant。如果您有一个指向-的指针，const那么程序的其他部分可能会在您不查看时更改该值。如果变量是用 定义的const，那么初始化后没有人可以更改它，但初始化仍然可以任意复杂。
