blocks|key|1454125|text|您可以使用goto。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1454126|while+(+...+)+{
+++switch(+...+)+{
+++++case+...:
+++++++++goto+exit_loop;

+++}
}
exit_loop:+;|code-block|syntax|javascript|1454127|entityMap^0|5|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|$]]

You can use <code>goto</code>.

<pre><code>while ( ... ) {
 switch( ... ) {
 case ...:
 goto exit_loop;

 }
}
exit_loop: ;
</code></pre>

blocks|key|1239595|text|另一种解决方案是将关键字continue与break结合使用，即：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1239596|for+(;;)+{
++++switch(msg->state)+{
++++case+MSGTYPE:
++++++++//+code
++++++++continue;+//+continue+with+loop
++++case+DONE:
++++++++break;
++++}
++++break;
}|code-block|syntax|javascript|1239597|使用continue语句结束希望循环继续的每个case标签，并使用break语句结束应终止循环的case标签。|1239598|当然，只有在switch语句之后没有要执行的额外代码时，此解决方案才有效。|1239599|entityMap^0|C|8|L|5|0|0|2|8|X|5|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|M|3|N|5|6|7|11|8|@]|D|@]|E|$]]|$1|O|3|-4|5|6|7|12|8|@]|D|@]|E|$]]]|P|$]]

An alternate solution is to use the keyword <code>continue</code> in combination with <code>break</code>, i.e.:
<pre><code>for (;;) {
 switch(msg-&gt;state) {
 case MSGTYPE:
 // code
 continue; // continue with loop
 case DONE:
 break;
 }
 break;
}
</code></pre>
Use the <code>continue</code> statement to finish each case label where you want the loop to continue and use the <code>break</code> statement to finish case labels that should terminate the loop.
Of course this solution only works if there is no additional code to execute after the switch statement.

blocks|key|1454371|text|要做到这一点，一种简洁的方法是将其放入函数中：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1454372|int+yourfunc()+{

++++while(true)+{

++++++++switch(msg->state)+{
++++++++case+MSGTYPE:+//+...+
++++++++++++break;
++++++++//+...+more+stuff+...
++++++++case+DONE:
++++++++++++return;+
++++++++}

++++}
}|code-block|syntax|javascript|1454373|可选的(但“糟糕的做法”)：正如已经建议的，你可以使用goto，或者在开关中抛出一个异常。|1454374|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

A neatish way to do this would be to put this into a function:

<pre><code>int yourfunc() {

 while(true) {

 switch(msg-&gt;state) {
 case MSGTYPE: // ... 
 break;
 // ... more stuff ...
 case DONE:
 return; 
 }

 }
}
</code></pre>

Optionally (but 'bad practices'): as already suggested you could use a goto, or throw an exception inside the switch.

blocks|key|1454324|text|AFAIK+C%2B%2B中没有“双中断”或类似的构造。最接近的是goto+-虽然它的名字有不好的含义，但它存在于语言中是有原因的-只要小心和谨慎地使用，它是一个可行的选择。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1454325|entityMap^0|T|4|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

AFAIK there is no "double break" or similar construct in C++. The closest would be a <code>goto</code> - which, while it has a bad connotation to its name, exists in the language for a reason - as long as it's used carefully and sparingly, it's a viable option.

blocks|key|1454497|text|您可以将开关放入一个单独的函数中，如下所示：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1454498|bool+myswitchfunction()
{
++++switch(msg->state)+{
++++case+MSGTYPE:+//+...+
++++++++break;
++++//+...+more+stuff+...
++++case+DONE:
++++++++return+false;+//+**HERE,+I+want+to+break+out+of+the+loop+itself**
++++}
++++return+true;
}

while(myswitchfunction())
++++;|code-block|syntax|javascript|1454499|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|$]]

You could put your switch into a separate function like this:

<pre><code>bool myswitchfunction()
{
 switch(msg-&gt;state) {
 case MSGTYPE: // ... 
 break;
 // ... more stuff ...
 case DONE:
 return false; // **HERE, I want to break out of the loop itself**
 }
 return true;
}

while(myswitchfunction())
 ;
</code></pre>

blocks|key|1239526|text|即使你不喜欢goto，也不要使用异常来退出循环。下面的示例显示了它可能有多难看：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1239527|try+{
++while+(+...+)+{
++++switch(+...+)+{
++++++case+...:
++++++++throw+777;+//+I'm+afraid+of+goto
+++++}
++}
}
catch+(+int+)
{
}|code-block|syntax|javascript|1239528|我会使用this+answer中的goto。在这种情况下，goto将使代码比任何其他选项更清晰。我希望这个this问题会对我有所帮助。|offset|length|style|CODE|1239529|但是由于字符串while(true)，我认为在这里使用goto是唯一的选择。你应该考虑重构你的循环。我认为下面的解决方案：|1239530|bool+end_loop+=+false;
while+(+!end_loop+)+{
++++switch(+msg->state+)+{
++++case+MSGTYPE:+//+...+
++++++++break;
++++//+...+more+stuff+...
++++case+DONE:
++++++++end_loop+=+true;+break;
++++}
}|1239531|或者甚至是以下内容：|1239532|while+(+msg->state+!=+DONE+)+{
++++switch(+msg->state+)+{
++++case+MSGTYPE:+//+...+
++++++++break;
++++//+...+more+stuff+...
}|1239533|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/1420029/how-to-break-out-of-a-loop-from-inside-a-switch/1420038#1420038|1|https://stackoverflow.com/questions/24451/goto-usage^0|0|0|H|4|T|4|4|4|0|1H|4|1|0|7|B|R|4|0|0|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|15|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|16|8|@$I|17|J|18|K|L]|$I|19|J|1A|K|L]]|9|@$I|1B|J|1C|1|1D]|$I|1E|J|1F|1|1G]]|A|$]]|$1|M|3|N|5|6|7|1H|8|@$I|1I|J|1J|K|L]|$I|1K|J|1L|K|L]]|9|@]|A|$]]|$1|O|3|P|5|D|7|1M|8|@]|9|@]|A|$E|F]]|$1|Q|3|R|5|6|7|1N|8|@]|9|@]|A|$]]|$1|S|3|T|5|D|7|1O|8|@]|9|@]|A|$E|F]]|$1|U|3|-4|5|6|7|1P|8|@]|9|@]|A|$]]]|V|$W|$5|X|Y|Z|A|$10|11]]|12|$5|X|Y|Z|A|$10|13]]]]

Even if you don't like goto, do not use an exception to exit a loop. The following sample shows how ugly it could be:

<pre><code>try {
 while ( ... ) {
 switch( ... ) {
 case ...:
 throw 777; // I'm afraid of goto
 }
 }
}
catch ( int )
{
}
</code></pre>

I would use <code>goto</code> as in <a href="https://stackoverflow.com/questions/1420029/how-to-break-out-of-a-loop-from-inside-a-switch/1420038#1420038">this</a> answer. In this case <code>goto</code> will make code more clear then any other option. I hope that <a href="https://stackoverflow.com/questions/24451/goto-usage">this</a> question will be helpful.

But I think that using <code>goto</code> is the only option here because of the string <code>while(true)</code>. You should consider refactoring of your loop. I'd suppose the following solution:

<pre><code>bool end_loop = false;
while ( !end_loop ) {
 switch( msg-&gt;state ) {
 case MSGTYPE: // ... 
 break;
 // ... more stuff ...
 case DONE:
 end_loop = true; break;
 }
}
</code></pre>

Or even the following:

<pre><code>while ( msg-&gt;state != DONE ) {
 switch( msg-&gt;state ) {
 case MSGTYPE: // ... 
 break;
 // ... more stuff ...
}
</code></pre>

blocks|key|1454419|text|在这种情况下，没有用于跳出循环的C%2B%2B构造。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1454420|要么使用标志来中断循环，要么(如果合适的话)将代码提取到函数中并使用return。|offset|length|style|CODE|1454421|entityMap^0|0|Y|6|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

There's no C++ construct for breaking out of the loop in this case.

Either use a flag to interrupt the loop or (if appropriate) extract your code into a function and use <code>return</code>.

blocks|key|1240197|text|不，C%2B%2B没有这样的构造，因为关键字"break“已经保留用于退出开关块。或者，一个带有退出标志的do..while()就足够了。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1240198|do+{+
++++switch(option){
++++++++case+1:+..;+break;
++++++++...
++++++++case+n:+..+;break;
++++++++default:+flag+=+false;+break;
++++}
}+while(flag);|code-block|syntax|javascript|1240199|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|$]]

No, C++ does not have a construct for this, given that the keyword "break" is already reserved for exiting the switch block. Alternatively a do..while() with an exit flag could suffice.

<pre><code>do { 
 switch(option){
 case 1: ..; break;
 ...
 case n: .. ;break;
 default: flag = false; break;
 }
} while(flag);
</code></pre>

blocks|key|1454154|text|您可以使用goto，但我更喜欢设置一个停止循环的标志。然后打破开关。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1454155|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|$]]

You could potentially use goto, but I would prefer to set a flag that stops the loop. Then break out of the switch.

blocks|key|1454822|text|为什么不直接修复while循环中的条件，使问题消失呢？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1454823|while(msg->state+!=+DONE)
{
++++switch(msg->state)+{
++++case+MSGTYPE:+//+...+
++++++++break;
++++//+...+more+stuff+...
++++case+DONE:
++++++++//+We+can't+get+here,+but+for+completeness+we+list+it.
++++++++break;+//+**HERE,+I+want+to+break+out+of+the+loop+itself**
++++}
}|code-block|syntax|javascript|1454824|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|$]]

Why not just fix the condition in your while loop, causing the problem to disappear?

<pre><code>while(msg-&gt;state != DONE)
{
 switch(msg-&gt;state) {
 case MSGTYPE: // ... 
 break;
 // ... more stuff ...
 case DONE:
 // We can't get here, but for completeness we list it.
 break; // **HERE, I want to break out of the loop itself**
 }
}
</code></pre>

blocks|key|1454767|text|考虑到解释的深度，我很惊讶这是多么简单。这就是你需要的..。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1454768|bool+imLoopin+=+true;

while(imLoopin)+{

++++switch(msg->state)+{

++++++++case+MSGTYPE:+//+...+
++++++++++++break;

++++++++//+...+more+stuff+...

++++++++case+DONE:
++++++++++++imLoopin+=+false;
++++++++++++break;

++++}

}|code-block|syntax|javascript|1454769|哈哈！！真的!这就是你所需要的！一个额外的变量！|1454770|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

It amazes me how simple this is considering the depth of explanations... Here's all you need...

<pre><code>bool imLoopin = true;

while(imLoopin) {

 switch(msg-&gt;state) {

 case MSGTYPE: // ... 
 break;

 // ... more stuff ...

 case DONE:
 imLoopin = false;
 break;

 }

}
</code></pre>

LOL!! Really! That's all you need! One extra variable!

blocks|key|1240071|text|我想；|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1240072|while(msg->state+!=+mExit)+
{
++++switch(msg->state)+
++++{
++++++case+MSGTYPE:+//+...
+++++++++break;
++++++case+DONE:
++++++//++..+
++++++//++..
++++++msg->state+=mExit;
++++++break;
++++}
}
if+(msg->state+==mExit)
+++++msg->state+=DONE;|code-block|syntax|javascript|1240073|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|$]]

I think;

<pre><code>while(msg-&gt;state != mExit) 
{
 switch(msg-&gt;state) 
 {
 case MSGTYPE: // ...
 break;
 case DONE:
 // .. 
 // ..
 msg-&gt;state =mExit;
 break;
 }
}
if (msg-&gt;state ==mExit)
 msg-&gt;state =DONE;
</code></pre>

blocks|key|1240110|text|我遇到了同样的问题，并使用一个标志解决了这个问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1240111|bool+flag+=+false;
while(true)+{
++++switch(msg->state)+{
++++case+MSGTYPE:+//+...+
++++++++break;
++++//+...+more+stuff+...
++++case+DONE:
++++++++flag+=+true;+//+**HERE,+I+want+to+break+out+of+the+loop+itself**
++++}
++++if(flag)+break;
}|code-block|syntax|javascript|1240112|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|$]]

I got same problem and solved using a flag.

<pre><code>bool flag = false;
while(true) {
 switch(msg-&gt;state) {
 case MSGTYPE: // ... 
 break;
 // ... more stuff ...
 case DONE:
 flag = true; // **HERE, I want to break out of the loop itself**
 }
 if(flag) break;
}
</code></pre>

blocks|key|1240287|text|因为switch使用break从switch+(而不是从while(1))中断，所以它需要goto-statement：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1240288|while(1)+{
++++switch+(*p)+{
++++++case+'+':
++++++++p%2B%2B;
++++++++break;
++++++case+'\n':
++++++++p%2B%2B;+*s=p;+return(i);
++++++case+'\0':
++++++++*s=p;+return(i);
++++++default:
++++++++token[i]=p;
++++++++i%2B%2B;
++++++++p%2B%2B;
++++++++goto+ex1;
++++};
++};
++ex1:|code-block|syntax|javascript|1240289|我不能将多个case添加到同一行中，如下所示：|1240290|大小写‘'，'\t'：|1240291|它会是|1240292|案例‘'：案例'\t'：|1240293|这就是为什么也许这里使用的中断...|1240294|看起来最常见的案例应该放在列表的顶部，以使程序运行得更快。它可能没有并行执行来搜索不同的案例。|1240295|因此，标准c可能缺少有关此切换的一些方法：https://blog.hackajob.co/better-c-switch-statements-for-a-range-of-values/+=>允许您在切换表达式中使用<、>、<=和>=运算符|1240296|我在想(如果c语言的语法改变了)它应该是这样的：|1240297|switch+(c)+{
++case+>=+5:
+++++...+op1
++endcase;
++case+==+1:
++case+==+3:
+++++...+op2
++endcase;
++default:
++++...
};|1240298|其中，当c等于1或3时执行op2，并且当c大于或等于5时执行op1。因为对于等于或大于/小于的比较将以类似的方式容易地发生。|1240299|++while(1)+{
++++switch+(c)+{
++++++case+>=+2:
+++++++++...+op1
++++++case+<=+5:
+++++++++...+op2
++++++break;
++++++default:
++++++++...
++++};
++};|1240300|本例中，对大于2的c执行op1，对2<=c<=5执行op2，break从while-loop退出。|1240301|entityMap|0|LINK|mutability|MUTABLE|url|https://blog.hackajob.co/better-c-switch-statements-for-a-range-of-values/^0|2|6|A|5|G|6|S|8|19|4|0|0|0|0|0|0|0|0|L|22|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1G|8|@$9|1H|A|1I|B|C]|$9|1J|A|1K|B|C]|$9|1L|A|1M|B|C]|$9|1N|A|1O|B|C]|$9|1P|A|1Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|1R|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|1S|8|@]|D|@]|E|$]]|$1|M|3|N|5|6|7|1T|8|@]|D|@]|E|$]]|$1|O|3|P|5|6|7|1U|8|@]|D|@]|E|$]]|$1|Q|3|R|5|6|7|1V|8|@]|D|@]|E|$]]|$1|S|3|T|5|6|7|1W|8|@]|D|@]|E|$]]|$1|U|3|V|5|6|7|1X|8|@]|D|@]|E|$]]|$1|W|3|X|5|6|7|1Y|8|@]|D|@$9|1Z|A|20|1|21]]|E|$]]|$1|Y|3|Z|5|6|7|22|8|@]|D|@]|E|$]]|$1|10|3|11|5|H|7|23|8|@]|D|@]|E|$I|J]]|$1|12|3|13|5|6|7|24|8|@]|D|@]|E|$]]|$1|14|3|15|5|H|7|25|8|@]|D|@]|E|$I|J]]|$1|16|3|17|5|6|7|26|8|@]|D|@]|E|$]]|$1|18|3|-4|5|6|7|27|8|@]|D|@]|E|$]]]|19|$1A|$5|1B|1C|1D|E|$1E|1F]]]]

Because the <code>switch</code> uses the <code>break</code> to break out from the <code>switch</code> (not from the <code>while(1)</code>), it needs the <code>goto</code>-statement:
<pre><code>while(1) {
 switch (*p) {
 case ' ':
 p++;
 break;
 case '\n':
 p++; *s=p; return(i);
 case '\0':
 *s=p; return(i);
 default:
 token[i]=p;
 i++;
 p++;
 goto ex1;
 };
 };
 ex1:
</code></pre>
I can't add multiple case to same line like:
case ' ','\t':
it would be
case ' ': case '\t':
That's why maybe the break used here...
It looks the most frequent cases should be placed at the top of the list to make the program run faster.
It may not have parallel execution for searching the different cases.
It is possible that the standard c then has missing some methods about this switching:
<a href="https://blog.hackajob.co/better-c-switch-statements-for-a-range-of-values/" rel="nofollow noreferrer">https://blog.hackajob.co/better-c-switch-statements-for-a-range-of-values/</a>
=&gt; allows you to use the &lt;, &gt;, &lt;=, and &gt;= operators in a switch expression
I was thinking that it should be (if c-language syntax changed) like:
<pre><code>switch (c) {
 case &gt;= 5:
 ... op1
 endcase;
 case == 1:
 case == 3:
 ... op2
 endcase;
 default:
 ...
};
</code></pre>
where op2 is executed when c is equal to 1 or 3 and when c is larger than or equal to 5 op1 is executed.
Because comparison for equal or larger/smaller than would occur easily in similar manner.
<pre><code> while(1) {
 switch (c) {
 case &gt;= 2:
 ... op1
 case &lt;= 5:
 ... op2
 break;
 default:
 ...
 };
 };
</code></pre>
this case op1 is executed for c larger than 2 and op2 executed for 2&lt;=c&lt;=5 and break exits it from while-loop.

blocks|key|1454663|text|最简单的方法是在执行切换之前放置一个简单的IF，并且IF测试退出循环的条件..........尽可能的简单|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1454664|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|$]]

The simplest way to do it is to put a simple IF before you do the SWITCH , and that IF test your condition for exiting the loop .......... as simple as it can be

blocks|key|1239747|text|C%2B%2B中的break关键字只终止嵌套最多的封闭迭代或switch语句。因此，您不能直接在switch语句中中断while+(true)循环；但是您可以使用以下代码，我认为这是解决此类问题的一个很好的模式：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1239748|for+(;+msg->state+!=+DONE;+msg+=+next_message())+{
++++switch+(msg->state)+{
++++case+MSGTYPE:
++++++++//...
++++++++break;

++++//...
++++}
}|code-block|syntax|javascript|1239749|如果您需要在msg->state等于DONE时执行某些操作(例如运行清理例程)，则将该代码紧跟在for循环之后；即，如果您当前具有：|1239750|while+(true)+{
++++switch+(msg->state)+{
++++case+MSGTYPE:
++++++++//...+
++++++++break;

++++//...

++++case+DONE:
++++++++do_cleanup();
++++++++break;
++++}

++++if+(msg->state+==+DONE)
++++++++break;

++++msg+=+next_message();
}|1239751|然后改用：|1239752|for+(;+msg->state+!=+DONE;+msg+=+next_message())+{
++++switch+(msg->state)+{
++++case+MSGTYPE:
++++++++//...
++++++++break;

++++//...
++++}
}

assert(msg->state+==+DONE);
do_cleanup();|1239753|entityMap^0|5|5|Q|6|18|6|1J|C|0|0|6|A|I|4|1C|3|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]|$9|Z|A|10|B|C]|$9|11|A|12|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|13|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|14|8|@$9|15|A|16|B|C]|$9|17|A|18|B|C]|$9|19|A|1A|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|1B|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|1C|8|@]|D|@]|E|$]]|$1|Q|3|R|5|H|7|1D|8|@]|D|@]|E|$I|J]]|$1|S|3|-4|5|6|7|1E|8|@]|D|@]|E|$]]]|T|$]]

The <code>break</code> keyword in C++ only terminates the most-nested enclosing iteration or <code>switch</code> statement. Thus, you couldn't break out of the <code>while (true)</code> loop directly within the <code>switch</code> statement; however you could use the following code, which I think is an excellent pattern for this type of problem:

<pre><code>for (; msg-&gt;state != DONE; msg = next_message()) {
 switch (msg-&gt;state) {
 case MSGTYPE:
 //...
 break;

 //...
 }
}
</code></pre>

If you needed to do something when <code>msg-&gt;state</code> equals <code>DONE</code> (such as run a cleanup routine), then place that code immediately after the <code>for</code> loop; i.e. if you currently have:

<pre><code>while (true) {
 switch (msg-&gt;state) {
 case MSGTYPE:
 //... 
 break;

 //...

 case DONE:
 do_cleanup();
 break;
 }

 if (msg-&gt;state == DONE)
 break;

 msg = next_message();
}
</code></pre>

Then use instead:

<pre><code>for (; msg-&gt;state != DONE; msg = next_message()) {
 switch (msg-&gt;state) {
 case MSGTYPE:
 //...
 break;

 //...
 }
}

assert(msg-&gt;state == DONE);
do_cleanup();
</code></pre>

blocks|key|1454786|text|while(MyCondition)+{
switch(msg->state)+{
case+MSGTYPE:+//+...+
++++break;
//+...+more+stuff+...
case+DONE:
+++MyCondition=false;+//+just+add+this+code+and+you+will+be+out+of+loop.
++++break;+//+**HERE,+you+want+to+break+out+of+the+loop+itself**
}
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1454787|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>while(MyCondition) {
switch(msg-&gt;state) {
case MSGTYPE: // ... 
 break;
// ... more stuff ...
case DONE:
 MyCondition=false; // just add this code and you will be out of loop.
 break; // **HERE, you want to break out of the loop itself**
}
}
</code></pre>

blocks|key|1239643|text|如果我记得很清楚C%2B%2B语法，您可以向break语句添加标签，就像goto一样。所以你想要的东西很容易写出来：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1239644|while(true)+{
++++switch(msg->state)+{
++++case+MSGTYPE:+//+...
++++++++break;
++++//+...+more+stuff+...
++++case+DONE:
++++++++break+outofloop;+//+**HERE,+I+want+to+break+out+of+the+loop+itself**
++++}
}

outofloop:
//+rest+of+your+code+here|code-block|syntax|javascript|1239645|entityMap^0|I|5|W|4|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|L|$]]

If I remember C++ syntax well, you can add a label to <code>break</code> statements, just like for <code>goto</code>. So what you want would be easily written:

<pre><code>while(true) {
 switch(msg-&gt;state) {
 case MSGTYPE: // ...
 break;
 // ... more stuff ...
 case DONE:
 break outofloop; // **HERE, I want to break out of the loop itself**
 }
}

outofloop:
// rest of your code here
</code></pre>

blocks|key|1454789|text|++while(true)
++{
++++switch(x)
++++{
+++++case+1:
+++++{
++++++break;
+++++}
++++break;
+++case+2:
++++//some+code+here
+++break;
++default:
++//some+code+here
++}
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1454790|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code> while(true)
 {
 switch(x)
 {
 case 1:
 {
 break;
 }
 break;
 case 2:
 //some code here
 break;
 default:
 //some code here
 }
}
</code></pre>

I'm writing some code that looks like this:

<pre><code>while(true) {
 switch(msg-&gt;state) {
 case MSGTYPE: // ... 
 break;
 // ... more stuff ...
 case DONE:
 break; // **HERE, I want to break out of the loop itself**
 }
}
</code></pre>

Is there any direct way to do that?

I know I can use a flag, and break from the loop by putting a conditional break just after the switch. I just want to know if C++ has some construct for this already.

How to break out of a loop from inside a switch?

我正在写一些代码，看起来像这样：while(true) {    switch(msg->state) {    case MSGTYPE: // ...         break;    // ... more stuff ...    case DONE:        break; // **HERE, I want to break out of the loop itself**   

问如何从交换机内部打破循环？
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