c语言的label后面不能直接跟变量申明

    int x = 5;
    goto JUMP;
    printf("x is : %d
",x);
JUMP:
    int a = 0;  <=== 错误，lable后面不能申明变量，只能是表达式语句(statement)，哪怕是空语句..
    printf("%d",a);

    int x = 5;
    goto JUMP;
    printf("x is : %d
",x);
JUMP: ;     /// 空语句，正确
    int a = 0;     // 前面有空语句，正确
    printf("%d",a);

label只在函数内有效