仿照struct is_integral 实现struct not_int

#include <type_traits>
#include <iostream>

using namespace std;

template<typename T>
void doo(T t, true_type)
{
    cout << t << " is int!
";
}


template<typename T>
void doo(T t, false_type)
{
    cout << t << " is not int!
";
}


template<typename T>
struct not_int_helper
        : public false_type {};

//全特化
template<>
struct not_int_helper<int>
        : public true_type { };


template<typename T>
struct not_int_simple: public not_int_helper<T>::type
{ };


/**完整版！**/
//template<typename T>
//struct not_int_simple: public not_int_helper<typename remove_cv<T>::type>::type
//{ };


template<typename T>
T do_foo(T t){
    doo(t, not_int_simple<T>());
}

int main()
{
    do_foo<int>(3);
    do_foo<long>(2);
    do_foo<short>(1);
}

　　

仿照，struct is_integral 实现struct not_int。