blocks|key|1321560|text|关键字break将退出循环，而不会在循环条件中进行任何比较。如果使用i+=+15语法，则下一次循环将迭代以验证变量i是否大于10，如果大于10，则退出。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1321561|简而言之，break将在不考虑任何问题的情况下打破循环，而i+=+15将导致再进行一次迭代，以查看是否满足条件。|1321562|entityMap^0|3|5|Y|6|1L|1|0|5|5|T|6|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]|$9|M|A|N|B|C]|$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|H|3|-4|5|6|7|V|8|@]|D|@]|E|$]]]|I|$]]

The keyword <code>break</code> will just quit the loop without any comparison made in the loop condition. If you use <code>i = 15</code> syntax, the loop will iterate next time to verify whether the variable <code>i</code> is greater than 10, if so, then quit.
In short words, <code>break</code> will break the loop without thinking anything, whereas <code>i = 15</code> will lead one more iteration to look if the condition satisfies it.

blocks|key|1837350|text|如果选择while循环，则可以在while循环中使条件为false。但在这种情况下，使用中断是有意义的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1837351|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

if you choose while loop you can prefer to make condition false in the while loop. But in this case using break make sense.

blocks|key|1325343|text|你是对的!实际上，break关键字用于中断循环的速度非常快！|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1325344|在您的示例中，如果您使用A行，那么一旦控件到达该语句，它将立即中断循环。|1325345|另一方面，如果您使用B行，那么首先将执行赋值，然后控件将再次进入条件检查，当条件变为false时，它将退出循环！|1325346|entityMap^0|9|5|0|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|O|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|P|8|@]|D|@]|E|$]]|$1|J|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|K|$]]

You're right! Actually <code>break</code> keyword is very faster for breaking loop!
In your example, if you use line A, then as soon as control reaches this statement, it will immediately break the loop.
On the other hand, if you use line B, then first the assignment will be performed and again the control will go to the condition checking and when the condition will get false then it will exit from the loop!

blocks|key|1321645|text|让我们编译以下代码并查看程序集：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1321646|#include+<stdio.h>

int+loop_with_break()+{
++++for+(int+i+=+0;+i+<+10;+i+%2B%2B)+{
++++++++puts("Hello,+world!");
++++++++if+(i+==+3)+{
++++++++++++break;
++++++++}
++++}
}

int+loop_with_assignment()+{
++++for+(int+i+=+0;+i+<+10;+i+%2B%2B)+{
++++++++puts("Hello,+world!");
++++++++if+(i+==+3)+{
++++++++++++i+=+10;
++++++++}
++++}
}

int+main()+{
++++loop_with_break();
++++loop_with_assignment();
}|code-block|syntax|javascript|1321647|​|1321648|📷|atomic|offset|length|1321649|1321650|正如您所看到的，当您使用break，如果i+==+3，它将直接跳出循环到函数的末尾，而如果使用i+=+10，它会将i设置为10，将其增加1，然后进行比较，这要慢一些。但是，这是在编译时没有优化的。如果您使用优化，它们最终都会变成相同的东西。但是，由于break更具可读性，而且不能保证这些优化，所以您应该使用它来打破循环。|style|CODE|1321651|entityMap|0|IMAGE|mutability|IMMUTABLE|imageUrl|https://developer.qcloudimg.com/http-save/yehe-900000/c26917c74193e5ac18c5f60de1ad227a.png|imageAlt|1|https://developer.qcloudimg.com/http-save/yehe-900000/a809974c2b68c53c714e9c101757dba8.png^0|0|0|0|0|1|0|0|0|1|1|0|C|5|K|6|1B|6|1L|1|3H|5|0^^$0|@$1|2|3|4|5|6|7|13|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|14|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|15|8|@]|9|@]|A|$]]|$1|I|3|J|5|K|7|16|8|@]|9|@$L|17|M|18|1|19]]|A|$]]|$1|N|3|J|5|K|7|1A|8|@]|9|@$L|1B|M|1C|1|1D]]|A|$]]|$1|O|3|P|5|6|7|1E|8|@$L|1F|M|1G|Q|R]|$L|1H|M|1I|Q|R]|$L|1J|M|1K|Q|R]|$L|1L|M|1M|Q|R]|$L|1N|M|1O|Q|R]]|9|@]|A|$]]|$1|S|3|-4|5|6|7|1P|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|Z|10|-4]]|11|$5|V|W|X|A|$Y|12|10|-4]]]]

Let's compile the following code and look at the assembly:
<pre class="lang-c prettyprint-override"><code>#include &lt;stdio.h&gt;

int loop_with_break() {
 for (int i = 0; i &lt; 10; i ++) {
 puts(&quot;Hello, world!&quot;);
 if (i == 3) {
 break;
 }
 }
}

int loop_with_assignment() {
 for (int i = 0; i &lt; 10; i ++) {
 puts(&quot;Hello, world!&quot;);
 if (i == 3) {
 i = 10;
 }
 }
}

int main() {
 loop_with_break();
 loop_with_assignment();
}
</code></pre>
<a href="https://i.stack.imgur.com/3cjmz.png" rel="noreferrer"><img src="https://i.stack.imgur.com/3cjmz.png" alt="assembly of loop with break" /></a>
<a href="https://i.stack.imgur.com/T9Yqw.png" rel="noreferrer"><img src="https://i.stack.imgur.com/T9Yqw.png" alt="assembly of loop with assignment" /></a>
As you can see, when you use <code>break</code>, if <code>i == 3</code>, it'll jump straight out of the loop to the end of the function, whereas if you use <code>i = 10</code>, it'll set <code>i</code> to 10, increment it by 1, then do the comparison, which is slower. However, this was compiled with no optimizations. If you use optimizations, they both end up becoming the same thing. However, since <code>break</code> is more readable and these optimizations are not guaranteed, you should use it for breaking out of loops.

Is break the most efficient way to exit a loop? In the code snippet below, would line A or line B be the more efficient way to exit the loop? Any links to material on how the break instruction works under the hood would be appreciated.
<pre><code>for (int i = 0; i &lt; 10; i++) {
 cout &lt;&lt; i &lt;&lt; endl;
 if (i == 3) {
 break; // A
 i = 15; // B
 }
 }
</code></pre>
I assume the difference is trivial in most situations, and that A is faster because B requires an assignment, an increment, and then a comparison, but I don't actually know how break works and it's better to know than assume. Thanks!

Is the Break keyword the most efficent way to exit a for loop? C/C++

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。

页面排版不美观，阅读体验差。

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中断是退出循环最有效的方法吗？在下面的代码片段中，A行还是B行是退出循环的更有效的方法？任何链接的材料如何打破指示下的引擎盖，将不胜感激。for (int i = 0; i < 10; i++) { cout << i << endl; if (i == 3) { break...

问Break关键字是退出for循环最有效的方法吗？C/C++
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