blocks|key|4009390|text|使用变量指示是否需要退出：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4009391|bool+exit_program+=+false;

while(+!exit_program+&&+SDL_WaitEvent(&event1)+)
{
++++for(+/*+...+*/+)
++++{
++++++++exit_program+=+true;
++++}
}|code-block|syntax|javascript|4009392|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Use a variable to indicate the need to exit:

<pre><code>bool exit_program = false;

while( !exit_program &amp;&amp; SDL_WaitEvent(&amp;event1) )
{
 for( /* ... */ )
 {
 exit_program = true;
 }
}
</code></pre>

blocks|key|2374450|text|这个问题还有另一个答案，我想我应该在每个人都反对我之前说出来。使用变量当然是一种“好”的方法。然而，仅仅为了跳出循环而创建额外的变量似乎有点过头了，对吧？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2374451|所以，是的，这次goto是完美的解决方案。很清楚你在用它做什么，你没有使用另一个变量，代码保持简短，可维护和可读性。|offset|length|style|CODE|2374452|goto语句是糟糕的实践，基本上是基本时代的残余，当时它是改变代码流的唯一方法。然而，现在我们“知道得更清楚了”，并且说goto或任何其他结构都不好，这并不能解决问题。对于你试图用它解决的一个特定问题来说，这可能是不好的(人们试图用goto解决的大多数问题也是如此)。但是，在适当的情况下(就像这里)，这是可以的。当然，我不想在这里开始辩论。Goto就像一个非常强大的工具(例如，大锤)。它有它的用途，你不能说一个工具是完全不好的；它是用户以错误的方式使用它。|2374453|entityMap^0|0|8|4|0|1O|4|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|M|8|@$D|N|E|O|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|P|8|@$D|Q|E|R|F|G]]|9|@]|A|$]]|$1|J|3|-4|5|6|7|S|8|@]|9|@]|A|$]]]|K|$]]

There's another answer to that, and I think I should say it before everyone will downvote me.
Using a variable is certainly a "good" way to do it. However, the creating additional variable just to jump out of the loop seems a bit of overkill, right?

So yes, this time <code>goto</code> is perfect solution. It's perfectly clear what you are doing with it, you are not using another variable and the code remains short, maintainable and readable.

The statement goto is bad practice is mostly a remnant of the BASIC times, when it was quite the only way of changing code flow. However, now we "know better", and saying that the <code>goto</code> or any other construction is bad, just doesn't cut it. It can be bad for one particular problem you are trying to solve with it (and it's the case with most of the problems that people try to solve with goto). However, given the right circumstances (like here) it's OK. I don't want to start a debate here, of course. Goto is like a very powerful tool (sledgehammer, for example). It has its uses and you can't say a tool is totally bad; it's the user using it in the wrong way.

blocks|key|4100574|text|不需要额外变量和goto的解决方案|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4100575|while(SDL_WaitEvent(&event1))
{
++++size_t+i;
++++for(i+=+0;+i+<+MainMenuOptions.size();i%2B%2B)
++++{
++++++++if(/*+...+*/)
++++++++{
++++++++++++break;
++++++++}
++++}
++++if+(i+<+MainMenuOptions.size())
++++++++break;
}|code-block|syntax|javascript|4100576|entityMap^0|8|4|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

A solution without additional variable and <code>goto</code>:

<pre><code>while(SDL_WaitEvent(&amp;event1))
{
 size_t i;
 for(i = 0; i &lt; MainMenuOptions.size();i++)
 {
 if(/* ... */)
 {
 break;
 }
 }
 if (i &lt; MainMenuOptions.size())
 break;
}
</code></pre>

blocks|key|2242418|text|常见的解决方案是将这些东西放入它自己的函数中并从中返回：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2242419|inline+SDL_Event+do_it()
{
++++SDL_Event+event;
++++while(SDL_WaitEvent(&event))
++++++++for(std::size_t+i+=+0;+i+<+MainMenuOptions.size();+%2B%2Bi)
++++++++++++if(/*...*/)
++++++++++++++++return+event;
++++return+event;+//+or+whatever+else+suits,+I+know+too+little+about+your+code
}|code-block|syntax|javascript|2242420|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

The common solution is to put this stuff into its own function and return from that: 

<pre><code>inline SDL_Event do_it()
{
 SDL_Event event;
 while(SDL_WaitEvent(&amp;event))
 for(std::size_t i = 0; i &lt; MainMenuOptions.size(); ++i)
 if(/*...*/)
 return event;
 return event; // or whatever else suits, I know too little about your code
}
</code></pre>

blocks|key|2374626|text|第一点:国际海事组织，你试图把太多东西包装在一个地方，最后得到一些相当难以理解的东西--有些人必须通读整个长长的比较集，才能理解这应该实现的任何目标。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2374627|第二点:使用显式循环遍历标准集合通常是错误的--这也不例外。标准库已经有一个算法来完成与您的循环相同的基本任务。最好使用它，而不是自己重新编写它。|2374628|template+<class+T>
bool+in_range(T+a,+T+b,+T+c)+{+
++++return+(a+>+b)+&&+(a+<+b%2Bc);
}

class+in_rect+{
+++point+p;
public:
+++in_rect(point+const+&p)+:+p(p)+{}

+++//+Not+sure+of+the+type+of+objects+in+MainMenuOptions,+so+just+T+for+now.
+++//+
+++bool+operator()(T+const+&m)+{
+++++++return+in_range(p.x,+m.GetX(),+m.GetWidth())+
+++++++++++&&+in_range(p.y,+m.GetY(),+m.GetHeight());
+++}
};

SDL_Event+event1;

while+(SDL_WaitEvent(&event1))
++++if+(std::any_of(MainMenuOptions.begin(),+MainMenuOptions.end(),
++++++++++++++++++++in_rect(event1.button))++++++
++++++++break;|code-block|syntax|javascript|2374629|一旦我们解决了其他问题，就不再需要(甚至不再使用)+goto。我们没有采取任何明确的步骤来删除它，但是当其他问题被修复后(特别是用适当的算法替换循环)，它的用途就消失了。|offset|length|style|CODE|2374630|我想我应该先发制人地评论一下代码总行的增加:是的，有更多的代码行。这是什么？如果我们真的想这样做，我们可以使用相同的基本方法，但我们不需要定义in_rect和in_range，我们基本上只需要从原始if语句中提取条件并将其填充到一个lambda中即可。虽然我很高兴lambdas被添加到C%2B%2B中，但在这种情况下，我对使用它并不感到兴奋。它将去掉goto，但一般来说，代码几乎和它开始时一样不可读。|2374631|简单地说，行数并不是测量任何东西的好方法。|2374632|entityMap^0|0|0|0|Q|4|0|1Z|7|27|8|2R|2|4S|4|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|W|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|X|8|@$K|Y|L|Z|M|N]]|9|@]|A|$]]|$1|O|3|P|5|6|7|10|8|@$K|11|L|12|M|N]|$K|13|L|14|M|N]|$K|15|L|16|M|N]|$K|17|L|18|M|N]]|9|@]|A|$]]|$1|Q|3|R|5|6|7|19|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]]|T|$]]

First point: IMO, you're trying to wrap too much up into a single place, and ending up with something that's fairly difficult to understand -- somebody has to read through that entire long set of comparisons before they can understand any of what this is supposed to accomplish at all.

Second point: using an explicit loop to iterate over a standard collection is usually a mistake -- and this is no exception. The standard library already has an algorithm to accomplish the same basic thing as your loop. It's better to use that than write it again yourself.

<pre><code>template &lt;class T&gt;
bool in_range(T a, T b, T c) { 
 return (a &gt; b) &amp;&amp; (a &lt; b+c);
}

class in_rect {
 point p;
public:
 in_rect(point const &amp;p) : p(p) {}

 // Not sure of the type of objects in MainMenuOptions, so just T for now.
 // 
 bool operator()(T const &amp;m) {
 return in_range(p.x, m.GetX(), m.GetWidth()) 
 &amp;&amp; in_range(p.y, m.GetY(), m.GetHeight());
 }
};

SDL_Event event1;

while (SDL_WaitEvent(&amp;event1))
 if (std::any_of(MainMenuOptions.begin(), MainMenuOptions.end(),
 in_rect(event1.button)) 
 break;
</code></pre>

Once we fix the other problems, there's simply no longer any need (or even use) for the <code>goto</code>. We haven't taken any steps explicitly intended to remove it, but when the other problems have been fixed (especially, replacing the loop with an appropriate algorithm), the use for it has disappeared.

I suppose I should preemptively comment on the increase in the total number of lines of code: yes, there are more lines of code. What of it? If we really wanted to, we could use the same basic approach, but instead of defining <code>in_rect</code> and <code>in_range</code>, we'd basically just take the condition from the original <code>if</code> statement and stuff it into a lambda. While I'm very happy that lambdas have been added to C++, in this case I'm not excited about using it. It would get rid of the <code>goto</code>, but in general the code would be almost as unreadable as it started out.

Simply put, the number of lines isn't a good way to measure much of anything.

I've been messing around with C++ SDL for a few days now and I've come across an interesting problem.

<pre><code>SDL_Event event1;
while(SDL_WaitEvent(&amp;event1))
{
 for(size_t i = 0; i &lt; MainMenuOptions.size();i++)
 {
 if(event1.button.x &gt; MainMenuOptions.at(i).GetX() &amp;&amp; event1.button.x &lt; (MainMenuOptions.at(i).GetX() + MainMenuOptions.at(i).GetWidth()) 
 &amp;&amp; event1.button.y &gt; MainMenuOptions.at(i).GetY() &amp;&amp; event1.button.y &lt; (MainMenuOptions.at(i).GetY() + MainMenuOptions.at(i).GetHeight()))
 {
 break;
 }
 }
}
</code></pre>

When I use break in the for loop its going to break out of the for loop instead of the while loop. How would I break out the while loop instead without using the goto statement? (the goto statement is bad programming, I heard)

C++ SDL Breaking out of while loop

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

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我已经使用C++ SDL几天了，我遇到了一个有趣的问题。SDL_Event event1;while(SDL_WaitEvent(&event1)){ for(size_t i = 0; i < MainMenuOptions.size();i++) { if(event1.button.x ...

问C++ SDL中断while循环
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