Java i ++操作说明 [英] Java i++ operation explanation

问题描述

可能重复：

a + = b和a = + b之间有什么区别，还有++和++ a？

在&xdquo; x = x ++”？后x是什么

在Test1中，i将其值递增1并返回旧值并将其增量值保存在i变量中。但是在Test2中，我将其值增加1并返回其旧值，并且还会发生增量。他们是否为i中的变量分配了i的副本。 Test2中的操作步骤是什么。

In Test1 i increments its value by 1 and return old value and keep its incremental value in i variable. But in Test2 i increments its value by 1 and return its old value and the increment also occurred. Are they make a copy of i for the increment which is not assigning in the i variable. What is the operational step in Test2.

Test1

int i = 0;
System.out.print(i++);
System.out.print(i);

输出01

Test2

int i = 0;
i = i++;
System.out.println(i);

输出0

推荐答案

语句 i = i ++ 在Java中具有明确定义的行为。首先， i 的值被压入堆栈。然后，变量 i 递增。最后，弹出堆栈顶部的值并将其分配到 i 。最终结果是没有任何反应 - 智能优化器可以删除整个语句。

The statement i = i++ has well-defined behavior in Java. First, the value of i is pushed on a stack. Then, the variable i is incremented. Finally, the value on top the stack is popped off and assigned into i. The net result is that nothing happens -- a smart optimizer could remove the whole statement.

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