typedef struct
{int a;
}TestType;int main()
{enable_if <1, TestType>::type test1;							//正确test1.a = 100;enable_if <is_integral<int>::value, TestType>::type test2;		//正确test1.a = 100;enable_if <0, TestType>::type test3;							//错误test1.a = 100;enable_if <is_integral<float>::value, TestType>::type test4;	//错误
}