在一个循环中，除了标准的布尔测试外，一个约束能测试二个特定的条件式。

In a loop, a guard can have two special conditions tested against in addition to the standard Boolean test.

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在框架的内容区中，一个生命线的顶部，循环约束6被放置在左上角。

Inside the frame's content area the loop's guard is placed towards the top left corner, on top of a lifeline.

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如果C99解除“变量声明块”的约束，为什么这样做在一个“循环”显示错误吗？

If C99 lifted "variable declaration at top of block" constraint, why doing so in a "for loop" showing error?

youdao

It expands. You change your constraints on your system, you heat it up some more, then you take the heat source away, and you put it back in contact with the atmosphere. And you cool it a little bit, change the constraints, cool it a little bit more, and heat, and you've got a closed cycle engine.

让它与大气接触冷却,改变约束，使它继续冷却，然后又再次加热,这就是循环热机，我们以前也研究过，更复杂的机器。

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