blocks|key|2045875|text|在switch块中声明变量是否无效？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2045876|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|$]]

Might it not be valid to declare a variable within a switch block?

blocks|key|1831722|text|不能在case语句的开头声明变量。创建一个测试用例，只包含这些内容，您将得到相同的错误。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1831723|它与在代码块中间声明变量无关-甚至采用了一种标准，允许在case语句的开头不让GCC接受声明。看起来，GCC将case标签视为行的一部分，因此不允许在那里进行声明。|1831724|一种简单的解决方法是在案例的开头加一个分号，这样声明就不在开头了。|1831725|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

You can't declare a variable at the beginning of a case statement. Make a test case that just consists of that and you'll get the same error.

It doesn't have to do with variables being declared in the middle of a block — even adopting a standard that allows that won't make GCC accept a declaration at the beginning of a case statement. It appears that GCC views the case label as part of the line and thus won't allow a declaration there.

A simple workaround is just to put a semicolon at the beginning of the case so the declaration is not at the start.

blocks|key|1831768|text|在C中，你只能在任何非declare语句之前，在代码块的开头声明变量。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1831769|{
+++/*+you+can+declare+variables+here+*/

+++/*+block+statements+*/

+++/*+You+can't+declare+variables+here+*/
}|code-block|syntax|javascript|1831770|在C%2B%2B中，您可以在需要的任何地方声明变量。|1831771|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|$]]

In C you only can declare variables at the begining of a block before any non-declare statements. 

<pre><code>{
 /* you can declare variables here */

 /* block statements */

 /* You can't declare variables here */
}
</code></pre>

In C++ you can declare variables any where you need them.

blocks|key|1831856|text|如何解决警告：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1831857|1.在case块的第一行插入一个;|offset|length|style|CODE|1831858|2.将代码放在大括号内|1831859|entityMap^0|0|G|1|0|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|$]]|$1|H|3|I|5|6|7|P|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|K|$]]

How to solve the warning:

1.Insert one <code>;</code> in the first line of your case block

2.Put codes inside braces

blocks|key|1831929|text|您可以在switch语句中创建变量，但必须在块中创建它，以便定义该变量的作用域。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1831930|示例：|1831931|switch(number){

++++case+1:
++++++++{
++++++++++++//+Create+object+here
++++++++++++//+object+is+defined+only+for+the+scope+of+this+block
++++++++}
++++++++break;
++++case+2:
++++++++{
++++++++++++//+etc.
++++++++}
++++++++break;
++++default:
++++++++break;

}|code-block|syntax|javascript|1831932|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|L|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|M|8|@]|9|@]|A|$G|H]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

You can create a variable within a switch statement but you will have to create it within a block so that the scope of that variable is defined.

Example:

<pre><code>switch(number){

 case 1:
 {
 // Create object here
 // object is defined only for the scope of this block
 }
 break;
 case 2:
 {
 // etc.
 }
 break;
 default:
 break;

}
</code></pre>

I think I'm going blind, because I can't figure out where the syntax error is in this code:

<pre><code>if( cell == nil ) {
 titledCell = [ [ [ TitledCell alloc ] initWithFrame:CGRectZero
 reuseIdentifier:CellIdentifier ] autorelease
 ];

 switch( cellNumber ) {
 case 1:
 NSString *viewDataKey = @"Name";
etc...
</code></pre>

When I try to compile it, I'm getting an Error: syntax error before '*' token on the last line.

Sorry for such a basic question, but what am I missing?

Can I declare variables inside an Objective-C switch statement?

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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我想我快看不见了，因为我找不出这段代码中的语法错误在哪里：if( cell == nil ) {    titledCell = [ [ [ TitledCell alloc ] initWithFrame:CGRectZero        reuseIdentifier:CellIdentifier ] autor...

问我可以在Objective-C switch语句中声明变量吗？
EN

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问我可以在Objective-C switch语句中声明变量吗？EN