有结构体＆QUOT;快＆QUOT;不是类 - 总体上还是在.NET框架？ [英] Are Structs "faster" than Classes - In general or in the .NET framework?
问题描述
由于结构是值类型，他们的数据是复制时，传递给方法作为参数。例如：
Since structs are value-types, their data is copied when passed into a method as an argument. Example:
int someInt = 7;
DoSomeMethod(someInt); // <-- This is passing the "value" 7.
到目前为止，容易理解，而你可能想知道我的问题是有效的...所以考虑以下几点：
So far, easy to understand, and you're probably wondering how my question is valid... so consider the following:
public struct TimmysStructOfGoodness
{
public int SomeInt1;
public int SomeInt2;
public int SomeInt3;
// ... later that day ...
public int SomeInt999;
}
和然后，参照以下code：
and then, with reference to the following code:
TimmysStructOfGoodness someStructOfGoodness = new blah blah blah...
DoSomeMethod(someStructOfGoodness); // <-- **HERE IS WHERE THE QUESTION APPLIES!**
难道上面的语句尝试分配RAM数兆复制我的价值型（结构）？
Does the above statement try to allocate several megs of ram to "copy" my value-type (struct)?
如果答案是肯定的 - 那么当/在哪里的快而行慢
If the answer is yes - then when/where is the line between "faster" and "slower"?
如果没有 - 那么为什么不呢？因为我所知道的价值类型，这应该是一个问题。
If no - then why not? Because what I know of value-types, this should be a problem.
主要免责声明：我知道这个有没有关系，为什么你会使用结构诗句一类的，我知道，我永远不会让一个结构与999字段 - 这是基本的内部和胆量和只是一个问题，类似：）
MAJOR DISCLAIMER: I know that this has nothing to do with why you would use a struct verses a class, and I know that I will never make a struct with 999 fields - this is just a question of underlying internals and guts and the like :)
推荐答案
（更新，感谢捐款来自其他用户）
(updated, thanks to contributions from other users)
不同于类，结构是在堆栈中创建。因此，它是更快实例（和销毁）一个结构不是一个类。
Unlike class, struct is created on stack. So, it is faster to instantiate (and destroy) a struct than a class.
除非（亚当·罗宾逊指出的）结构是在这种情况下，它被分配在堆中的类成员，以及其他一切。
Unless (as Adam Robinson pointed out) struct is a class member in which case it is allocated in heap, along with everything else.
在另一方面，每次分配结构或将它传递给一个函数的时候，它就会被复制。
On the other hand, every time you assign a structure or pass it to a function, it gets copied.
我不认为有一个结构大小的硬性限制。千字节肯定是太多了。 MSDN 说：
I don't think there's a hard limit for a struct size. Thousands of bytes is definitely too much. MSDN says:
除非你需要引用类型 语义，一类是小 大于16字节可以更有效地 通过该系统处理为一个结构。
Unless you need reference type semantics, a class that is smaller than 16 bytes may be more efficiently handled by the system as a struct.
<打击>这是 - 如果你需要按引用传递这使它成为一个类，无论大小
在第二个想法，你仍然可以通过结构由简单地引用在函数参数列表中指定裁判。
On the second thought, you can still pass struct by reference simply by specifying ref in the function parameter list.
所以，大的结构实际上是确定的，如果你通过引用传递，并作为类成员使用。
So, a large struct can actually be ok if you pass it by reference and use as a class member.
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