C中的挥发性变量是什么?举些例子?它是如何工作的 [英] what is volatile varaible in c? give some examples ?how its work

问题描述

C中的volatile变量是什么?举一些例子?它的工作方式

what is volatile varaible in c? give some examples ?how its work

推荐答案

当您将volatile 属性添加到变量中时，您所要做的就是告诉编译器

When you add the volatile attribute to a variable all you are doing is telling the compiler

"The value in this variable is subject to change at any time. Do not try to keep it in a register, or use a working copy of the value. Do not optimise it at all. Just leave it alone."

它旨在与中断和其他此类事件一起使用，这些事件不是在程序的正常执行过程中发生的，而是使用特定的内存来传输信息的.如果编译器不知道，它可能会很乐意优化.

It is intended for use with interrupts and other such events which do not happen as part of normal execution of your program but which use particular memory to transfer information. If the compiler did not know about it, it could happily optimise

while (bytesRecieved == 0)
   {
   }

设置为if条件而不是while，因为bytesRecieved无法在循环中进行修改.

into an if condition rather than a while, since bytesRecieved cannot be modified within the loop.

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