flex if(a is b){},flex if(a as b){},

题目

flex if(a is b){},flex if(a as b){},
定义一个变量 var a:b=c,

答案

var a:b=c;定义一个变量a,它是b类型的,赋了初值c；if(a is b){}, 如果a是b类型的,表达式返回布尔值true,不是返回布尔值false； if(a as b){}, 将a 强制转为b类型,如果能转,表达式将返回该a对象本身,如果a不为空,可...