c++ - std::cout 在具有静态存储持续时间的对象的构造函数中的使用

Question

在 C++98/C++03 中具有静态存储持续时间的对象的构造函数中使用 std::cout 是否安全？

从这个看来answer它不是，但它不包含标准中的任何引用。

只有在 C++11 和 C++14 中才安全吗？

Answer 1

来自 C++14 (N3797)，§27.4p2:

The objects are constructed and the associations are established at some time prior to or during the first time an object of class ios_base::Init is constructed, and in any case before the body of main begins exe- cution.295 The objects are not destroyed during program execution.296 The results of including in a translation unit shall be as if defined an instance of ios_base::Init with static storage duration. Similarly, the entire program shall behave as if there were at least one instance of ios_base::Init with static storage duration.

C++98 使用类似的术语，但没有“as if”子句。

基本上，这禁止在main之前使用以下内容:

#include <ostream>
extern std::ostream cout;