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is_class template in C++
In this article we will be discussing the working, syntax and examples of std::is_class template in C++ STL.
is_class template is used to check whether the defined type is class type not any other type.
What is a class?
A class is an user defined data type or a data structure which contains some data members or member functions which is declared with the keyword ‘class’.
Example
class abc {
int data_members;
void member_function();
};So, is_class template checks that the type T is a class, and returns the Boolean value true or false accordingly.
Syntax
template <class T> is_class;
Parameters
The template can have only parameter of type T, and check whether the given type is a class or not a class.
Return value
It returns a Boolean value, true if the given type is a class, and false if the given type is not a class.
Example
Input: class abc {
};
is_class<abc>::value;
Output: True
Input: union abc {
};
is_class<abc>::value;
Output: FalseExample
#include <iostream>
#include <type_traits>
using namespace std;
class TP_1 {
};
union TP_2 {
int var_1;
float var_2;
};
int main() {
cout << boolalpha;
cout << "checking for is_class template: ";
cout << "\nTP_1 class : "<<is_class<TP_1>::value;
cout << "\nTP_2 union : "<< is_class<TP_2>::value;
return 0;
}Output
If we run the above code it will generate the following output −
checking for is_class template: TP_1 class : true TP_2 union : false
Example
#include <iostream>
#include <type_traits>
using namespace std;
class TP_1 {
int var_1;
float var_2;
char var_3;
};
union TP_2 {
int var_1;
float var_2;
char var_3;
};
struct TP_3 {
int var_1;
float var_2;
char var_3;
};
int main() {
cout << boolalpha;
cout << "checking for is_class template: ";
cout << "\nTP_1 class : "<<is_class<TP_1>::value;
cout << "\nTP_2 union : "<< is_class<TP_2>::value;
cout << "\nTP_3 structure : "<< is_class<TP_3>::value;
return 0;
}Output
If we run the above code it will generate the following output −
checking for is_class template: TP_1 class : true TP_2 union : false TP_3 structure : true
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