a declaration cannot have a label

目录

• 1.问题
• 2.分析
• 3.解决
• 4.应对

1.问题

2.分析

经过一番查找，发现是编译器的自己解释的局限性所致，会产生误分析。

与之类似的常见现象，还有在使用switch时在case 后面申请变量会出现 error: a declaration cannot have a label 的提示。

从网上找到的答案如下：

Case statements are only ‘labels’. This means the compiler will interpret this as a jump directly to the label.The problem here is one of scope. Your curly brackets define the scope as everything inside the ‘switch’ statement. This means that you are left with a scope where a jump will be performed further into the code skipping the initialization. The correct way to handle this is to define a scope specific to that case statement and define your variable within it.

真是Kiss compiler's ass, make it happy!~

3.解决

1. 对于图中的错误，只需要将变更定义提前即可。

2. 对SWITCH-CASE语句，在CASE后面加括号就行，即

switch (c)
    case 1:
	{
    	int temp;
        if(xxx) {
            xxx;
        }
	}

4.应对

在使用GCC时，要将所有的warning转为error即可快速找出，即 -Wall,-Werror

在使用ARMCC时，就要每改动一个文件，就编译一次，确保保 0 warning , 0 error。