template <class T> struct is_enum;

// C++程序说明
// is_enum模板
  
#include <iostream>
#include <type_traits>
using namespace std;
  
class GFG1 {
};
enum class GFG2 { var1,
                  var2,
                  var3,
                  var4
};
  
// 驱动代码
int main()
{
    cout << boolalpha;
    cout << "is_enum:" << endl;
    cout << "GFG1: "
         << is_enum<GFG1>::value << endl;
    cout << "GFG2: "
         << is_enum<GFG2>::value << endl;
  
    return 0;
}

is_enum:
GFG1: false
GFG2: true

// C++程序说明
// is_enum模板
  
#include <iostream>
#include <type_traits>
using namespace std;
  
class GFG1 {
};
  
enum class GFG2 : int {};
  
// 驱动代码
int main()
{
    cout << boolalpha;
    cout << "is_enum:" << endl;
    cout << "GFG1: "
         << is_enum<GFG1>::value << '\n';
    cout << "GFG2: "
         << is_enum<GFG2>::value << '\n';
    cout << "int: "
         << is_enum<int>::value << '\n';
    return 0;
}

is_enum:
GFG1: false
GFG2: true
int: false