initialization of xxx is skipped by xxx

使用case或goto语句时，有时会碰到如下提示：
vc2008：initialization of xxx is skipped by xxx
gcc：crosses initialization of xxx

以case为例：

int main( void )
{
    int a = 2;

    switch (a)
    {
    case 0:
        int b = 0;
        break;
    case 1:
        cout << a << endl;
		break;
    default:
        break;
    }

    return 0;
}

codeblocks(gcc) 编译提示：
In function `int main()':
error: jump to case label
error:   crosses initialization of `int b'
error: jump to case label|
error:   crosses initialization of `int b'
warning: unused variable 'b'
=== Build finished: 4 errors, 1 warnings ===

codeblocks(vc2008) 编译提示：
error C2360: initialization of 'b' is skipped by 'case' label
error C2361: initialization of 'b' is skipped by 'default' label
=== Build finished: 2 errors, 0 warnings ===

问题出在 b 的作用域，b 只在"case 0"的情况下进行了初始化，如果是其他语句就会被跳过去，

改变 b 的作用域就可以了，一般使用{}就可以了

   ...
   case 0:
   {
        int b = 0;
   }
   break;
   ...