如何构造/实例化对象std :: cout [英] How is the object std::cout constructed/instantiated

问题描述

所以std :: cout是一个对象。

谢谢。

解决方案

它由 ios_base :: Init 构造。第一次创建对象时，会创建 cout 和朋友。如果最后一个对象被销毁， cout 和朋友被刷新（调用 .flush（））。

在C ++ 0x中，如果你包含< iostream> ，并且使用 cout 和朋友之后 #include 将使用构造的 cout 在C ++ 03中，据说

构建对象，并且在第一次之前或期间的某个时间建立关联时间，构造类 ios_base :: Init 的对象，并且在任何情况下在主体开始执行之前。

So std::cout is an object. My doubt is how/where is it constructed/instantiated.

Thanks.

解决方案

It's constructed by ios_base::Init. First time that object is created, cout and friends are created. If the last object is destroyed, cout and friends are flushed (calling .flush()).

In C++0x it will be guaranteed that if you include <iostream>, and use of cout and friends after the #include will use constructed cout and friends objects. In C++03, it is said that

The objects are constructed, and the associations are established at some time prior to or during first time an object of class ios_base::Init is constructed, and in any case before the body of main begins execution.

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