为什么gcc不会编译未初始化的全局常量？ [英] Why won't gcc compile uninitialized global const?

问题描述

当我尝试用g ++编译以下代码时：

  const int zero; 
 
 int main（）
 {
 return 0; 
 
 $ / code> 

我得到一个有关未初始化的const零的错误。我认为全局变量默认初始化为0 [1]？为什么这里不是这种情况？

VS编译这个罚款。

$ b [1]例如，请参阅 https://stackoverflow.com/a/10927293/331785

解决方案

div>

我的gcc略显冗长：

  $ g ++ zeroconst.c 
 zeroconst.c：1 ：11：error：uninitialized const'zero'[-fpermissive] 
  

我们看到 -fpermissive 选项将允许它编译。<​​/ p>

在

正如 href =http://gcc.gnu.org/wiki/VerboseDiagnostics#error:_uninitialized_const_.27d.27_.5B-fpermissive.5D.2C_note:_.27const_class_D.27_has_no_user-provided_default_constructor =nofollow noreferrer> GCC维基：

按照C ++标准（C ++ 03中的8.5 [decl.init]，第9段，C ++ 0x中的
第6段），G ++不允许使用const限定类型的对象
被默认初始化，除非类型有用户声明的默认
构造函数。无法编译的代码可以通过提供
初始化程序来修复...

When I try to compile the following with g++:

const int zero;

int main()
{
  return 0;
}

I get an error about an uninitialized const 'zero'. I thought that global variables were default initialized to 0 [1] ? Why isn't this the case here?
VS compiles this fine.

[1] For example, see https://stackoverflow.com/a/10927293/331785

解决方案

My gcc is slightly more verbose:

$ g++ zeroconst.c
zeroconst.c:1:11: error: uninitialized const ‘zero’ [-fpermissive]

We see that -fpermissive option will allow this to compile.

See this question on uninitialized const for a reference to C++ standard (the problem is C++-specific).

As cited at GCC wiki:

As mandated by the C++ standard (8.5 [decl.init], para 9 in C++03, para 6 in C++0x), G++ does not allows objects of const-qualified type to be default initialized unless the type has a user-declared default constructor. Code that fails to compile can be fixed by providing an initializer...

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