返回的对象分配给引用 [英] Returned object assigned to reference
问题描述
请考虑以下事项：
#include< iostream>
struct X
{
int x;
X（）{x = 6; }
};
X val（）
{
返回X（）; < br $>
}
int main（）
{
X& x = val（）;
X x2 = x;
std :: cout<< x.x<< " " << x2.x;
}
调用val（）返回的对象的生命周期是多少？我b / b
会认为它应该立即销毁，创建一个
悬空参考，但程序可以运行，返回的对象是
直到它的封闭范围结束了吗？
Consider the following:
#include <iostream>
struct X
{
int x;
X() { x = 6; }
};
X val()
{
return X();
}
int main()
{
X & x = val();
X x2 = x;
std::cout << x.x << " " << x2.x;
}
What is the lifetime of the object returned by the call to val()? I
would have thought it should be destroyed immediately, creating a
dangling reference, yet the program works, does the returned object
live until the end of it''s enclosing scope?
推荐答案
* Andrew Ward：
* Andrew Ward:
考虑以下内容：
#include< iostream>
struct X
{
int x;
X（）{x = 6; }
};
X val（）
{
返回X（）;
}
int main（）
{X / amp; x = val（）;
X x2 = x;
std :: cout<< x.x<< " " << x2.x;
}
调用val（）返回的对象的生命周期是多少？我原本认为它应该被立即销毁，创建一个悬挂引用，但程序可以工作，返回的对象是否存在直到它的封闭范围结束？
Consider the following:
#include <iostream>
struct X
{
int x;
X() { x = 6; }
};
X val()
{
return X();
}
int main()
{
X & x = val();
X x2 = x;
std::cout << x.x << " " << x2.x;
}
What is the lifetime of the object returned by the call to val()? I
would have thought it should be destroyed immediately, creating a
dangling reference, yet the program works, does the returned object
live until the end of it''s enclosing scope?
任何东西，因为这是未定义的行为。
对const的引用将是另一回事。
然后引用将在范围结束时有效。
-
答：因为它弄乱了人们通常阅读文本的顺序。
问：为什么这么糟糕？
A：热门发布。
问：什么是最烦人的事情usenet和电子邮件？
Anything, because this is Undefined Behavior.
A reference to const would be another matter.
Then the reference would be valid until the end of the scope.
--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?
你能解释一下你的意思吗？对const的引用将
是另一回事。 ;通过修改给出的例子。
Could you please explain what you mean by "A reference to const would
be another matter." by modifying the example given.
* Andrew Ward：
* Andrew Ward:
你能解释一下你的意思吗？ const将是另一回事。通过修改给出的例子。
Could you please explain what you mean by "A reference to const would
be another matter." by modifying the example given.
请引用您所回复的内容;我不知道你到底在说什么。
-
答：因为它弄乱了人们通常阅读文字的顺序。
问：为什么这么糟糕？
A：热门帖子。
问：usenet和电子邮件中最烦人的是什么？
Please quote what you''re replying to; I don''t know what the heck you''re
talking about.
--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?
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