const in C vs const in C++

Question

The given code compiles in C but fails in C++.

int main()
{
   const int x; /* uninitialized const compiles in C but fails in C++*/
}

What

Answer 1

The ISO standard says (in 8.5 [dcl.init] paragraph 9):

If no initializer is specified for an object, and the object is of (possibly cv-qualified) non-POD class type (or array thereof), the object shall be default-initialized; if the object is of const-qualified type, the underlying class type shall have a user-declared default constructor.

if you try the same example after modifying to this:

int main()
{
   /*Unless explicitly declared extern, a const object does not have
 external linkage and must be initialized*/
   extern const int x; 
   return 0;
}

it will get compiled. So this self explains the need of enforcing this error to c++, declaring const vars without initializing and extern linkage is of no use, so coder must have added it by mistake.