在C＃是什么敏++和++敏之间的区别？ [英] In C# what is the difference between myInt++ and ++myInt?

问题描述

我有一个很难理解有什么区别在C＃这种方式递增的变量之间：

I'm having a hard time understanding what the difference is between incrementing a variable in C# this way:

myInt++;

和

++myInt;

在将永远无论你使用哪一个？

When would ever matter which one you use?

我给voteCount ++为最佳答案。或者我应该给它++ voteCount ...

I'll give voteCount++ for the best answer. Or should I give it ++voteCount...

推荐答案

有是对自己写的时候（如图所示）没有区别 - 在这两种情况下会敏1递增

There is no difference when written on its own (as shown) - in both cases myInt will be incremented by 1.

不过是有区别的，当你在一个前pression，例如使用是这样的：

But there is a difference when you use it in an expression, e.g. something like this:

MyFunction(++myInt);
MyFunction(myInt++);

在第一种情况下，敏递增和新的/递增的值被传递给MyFunction的（）。在第二种情况下，敏的旧值传递给MyFunction的（）（但敏还在递增，因此调用该函数之前）。

In the first case, myInt is incremented and the new/incremented value is passed to MyFunction(). In the second case, the old value of myInt is passed to MyFunction() (but myInt is still incremented before the function is called).

另一个例子是这样的：

int myInt = 1;
int a = ++myInt;
// myInt is incremented by one and then assigned to a.
// Both myInt and a are now 2.
int b = myInt++;
// myInt is assigned to b and then incremented by one.
// b is now 2, myInt is now 3

BTW：作为唐在评论中指出，同样的规则也适用于递减操作，而这些操作正确的术语是：

BTW: as Don pointed out in a comment the same rules are also valid for decrement operations, and the correct terminology for these operations are:

++i; // pre-increment
i++; // post-increment
--i; // pre-decrement
i--; // post-decrement

由于乔恩斯基特所指出的：

其他人所示，其中它使
  差，并评论说，作为
  单个语句不作
  区别。

Others have shown where it makes a difference, and have commented that as a single statement it doesn't make a difference.

我想补充一点，它几乎
  总是一个坏主意，它用它
  有差别。我怀疑有
  也许有些时候它更
  可读有code，如：

I'd like to add that it's almost always a bad idea to use it where it makes a difference. I suspect there may be some times where it's more readable to have code such as:

Console.WriteLine("Foo: {0}", foo++);

  
  

比

than:

Console.WriteLine("Foo: {0}", foo);
foo++;

  
  

......但他们是非常罕见的！该
  这两个样品的后者使
  立即订购晶莹剔透 -
  前者需要一点思考
  （我脑子不好，反正）。想到
  可读性第一。

... but they're very rare! The latter of these two samples makes the ordering crystal clear immediately - the former requires a bit of thinking (to my poor brain, anyway). Think of the readability first.

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