int ++和++ int有什么区别？ [英] What is the difference between int++ and ++int?

问题描述

可能重复：

++ i和i ++之间有什么区别

pre decrement vs. post decrement

是的我是菜鸟，但我完全忘记了他们都做了什么。

Yes I'm a noob, but I completely forgot what they both do.

然而，我知道int ++只是在int的值上加一。

I know, however, that int++ just adds one to the value of int.

那么，什么是++ int？

So, what is ++int?

谢谢。

推荐答案

如果您正在谈论C（或类C语言），除非您使用，否则它们完全相同值：

If you're talking about C (or C-like languages), it's exactly the same unless you use the value:

int a = 10;
int b = a++;

在这种情况下， a 变为11 b 设置为10.这是后增量 - 在使用后增加。

In that case, a becomes 11 and b is set to 10. That's post-increment - you increment after use.

如果您将上面的那一行更改为：

If you change that line above to:

int b = ++a;

然后 a 仍然变为11但是 b 。这是因为它是预增量 - 你在使用之前增加。

then a still becomes 11 but so does b. That's because it's pre-increment - you increment before use.

注意它对于C ++类来说并不完全相同，有效率可以通过优先选择一个而不是另一个。但是既然你在谈论整数，那么C ++就像C一样。

Note that it's not quite the same thing for C++ classes, there are efficiencies that can be had by preferring one over the other. But since you're talking about integers, C++ acts the same as C.

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