【C/C++】error: a label can only be part of a statement and a declaration is not a statement

http://stackoverflow.com/questions/92396/why-cant-variables-be-declared-in-a-switch-statement

switch case:里不能声明变量

如果要声明需要给case加{}

Case statements are only 'labels'. This means the compiler will interpret this as a jump directly to the label. In C++, 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.