std::is_abstract
From Get docs
Cpp/docs/latest/types/is abstract
std::is_abstract
Defined in header <type_traits>
|
||
---|---|---|
|
(since C++11) |
If T
is an abstract class (that is, a non-union class that declares or inherits at least one pure virtual function), provides the member constant value
equal true
. For any other type, value
is false
.
If T
is a non-union class type, T
shall be a complete type; otherwise, the behavior is undefined.
Template parameters
T | - | a type to check |
Helper variable template
|
(since C++17) |
Inherited from std::integral_constant
Member constants
value [static] |
true if T is an abstract class 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>
|
Example
#include <iostream>
#include <type_traits>
struct A {
int m;
};
struct B {
virtual void foo();
};
struct C {
virtual void foo() = 0;
};
struct D : C {};
int main()
{
std::cout << std::boolalpha;
std::cout << std::is_abstract<A>::value << '\n';
std::cout << std::is_abstract<B>::value << '\n';
std::cout << std::is_abstract<C>::value << '\n';
std::cout << std::is_abstract<D>::value << '\n';
}
Output:
false
false
true
true
See also
(C++11) |
checks if a type is a non-union class type (class template) |
(C++11) |
checks if a type is a polymorphic class type (class template) |
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