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    std::is_object

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    Defined in header <type_traits>
    template< class T > struct is_object;
    		 (since C++11)
    See More

    std::is_object is a UnaryTypeTrait.

    If T is an object type (that is any possibly cv-qualified type other than function, reference, or void types), provides the member constant value equal true. For any other type, value is false.

    If the program adds specializations for std::is_object or std::is_object_v, the behavior is undefined.

    Template parameters

    T - a type to check

    Helper variable template

    template< class T > constexpr bool is_object_v = is_object<T>::value;
    		 (since C++17)
    [edit]

    Inherited from std::integral_constant

    Member constants

    value
    [static]
    		 true if T is an object type, false otherwise
    (public static member constant)

    Member functions

    operator bool
    		 converts the object to bool, returns value
    (public member function)
    operator()
    (C++14)
    		 returns value
    (public member function)

    Member types

    Type Definition
    value_type bool
    type std::integral_constant<bool, value>

    Possible implementation

    template<class T>
struct is_object : std::integral_constant<bool,
                       std::is_scalar<T>::value ||
                       std::is_array<T>::value ||
                       std::is_union<T>::value ||
                       std::is_class<T>::value> {};

    Example

    Run this code
    #include <iomanip>
#include <iostream>
#include <type_traits>
 
#define IS_OBJECT(...) \
    std::cout << std::boolalpha << std::left << std::setw(9) << #__VA_ARGS__ \
              << (std::is_object_v<__VA_ARGS__> ? " is object\n" \
                                                : " is not an object\n")

int main()
{
    class cls {};

    IS_OBJECT(void);
    IS_OBJECT(int);
    IS_OBJECT(int&);
    IS_OBJECT(int*);
    IS_OBJECT(int*&);
    IS_OBJECT(cls);
    IS_OBJECT(cls&);
    IS_OBJECT(cls*);
    IS_OBJECT(int());
    IS_OBJECT(int(*)());
    IS_OBJECT(int(&)());
}

    Output: 

    void      is not an object
int       is object
int&      is not an object
int*      is object
int*&     is not an object
cls       is object
cls&      is not an object
cls*      is object
int()     is not an object
int(*)()  is object
int(&)()  is not an object

    See also

    (C++11)
    		 checks if a type is a scalar type
    (class template) [edit]
    (C++11)
    		 checks if a type is an array type
    (class template) [edit]
    (C++11)
    		 checks if a type is a union type
    (class template) [edit]
    (C++11)
    		 checks if a type is a non-union class type
    (class template) [edit]