The std::is_abstract template of C++ STL is used to check whether the type is a abstract class type or not. It returns a boolean value showing the same.
Syntax:
template < class T > struct is_abstract;
Parameter: This template contains single parameter T (Trait class) to check whether T is a abstract class type or not.
Return Value: This template returns a boolean value as shown below:
- True: if the type is a abstract class.
- False: if the type is a non-abstract class.
Below programs illustrate the std::is_abstract template in C++ STL:
Program 1:
// C++ program to illustrate // std::is_abstract template #include <iostream> #include <type_traits> using namespace std;
struct gfg {
int m;
}; struct sam {
virtual void foo() = 0;
}; class raj : sam {
}; int main()
{ cout << boolalpha;
cout << "is_abstract:" << '\n' ;
cout << "gfg:" << is_abstract<gfg>::value << '\n' ;
cout << "sam:" << is_abstract<sam>::value << '\n' ;
cout << "raj:" << is_abstract<raj>::value << '\n' ;
return 0;
} |
Program 2:
// C++ program to illustrate // std::is_abstract template #include <iostream> #include <type_traits> using namespace std;
struct gfg {
virtual void foo();
}; class raj {
virtual void foo() = 0;
}; struct sam : raj {
}; class geek {
virtual void foo();
}; int main()
{ cout << std::boolalpha;
cout << "is_abstract:" << '\n' ;
cout << "gfg:" << is_abstract<gfg>::value << '\n' ;
cout << "raj:" << is_abstract<raj>::value << '\n' ;
cout << "sam:" << is_abstract<sam>::value << '\n' ;
cout << "geek:" << is_abstract<geek>::value << '\n' ;
return 0;
} |
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