is_abstract template in C++
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:
#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:
#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;
}
|
Last Updated :
19 Nov, 2018
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