std::is_trivially_copy_constructible in C/C++
Last Updated :
30 Mar, 2020
The std::is_trivially_copy_constructible template is a type that can be trivially constructed from a value or reference of the same type. This includes scalar types, trivially copy constructible classes and arrays of such types. This algorithm is about to test whether a type is trivially copied constructible or not. It returns the boolean value showing the same.
Header File:
#include <type_traits>
Template Class:
template <class T>
struct is_trivially_copy_constructible;
If T is_trivially_copy_constructible, then it inherits from true_type else inherits from false_type.
Syntax:
std::is_trivially_copy_constructible<int>::value
std::is_trivially_copy_constructible<class T>::value
Parameter: This template accepts a single parameter T(Trait class) to check if T is trivially copy constructible or not.
Return Value: This template return a boolean variable as shown below:
- True: If the type is trivially copy constructible.
- False: If the type is not trivially copy constructible.
Below programs illustrates the std::is_trivially_copy_constructible template in C/C++:
Program 1:
#include <iostream>
#include <type_traits>
using namespace std;
struct A {
};
struct B {
B( const B&) {}
};
struct C {
virtual void fn() {}
};
int main()
{
cout << boolalpha;
cout << "is_trivially_copy_constructible: "
<< endl;
cout << "int: " << is_trivially_copy_constructible< int >::value
<< endl;
cout << "A: " << is_trivially_copy_constructible<A>::value
<< endl;
cout << "B: " << is_trivially_copy_constructible<B>::value
<< endl;
cout << "C: " << is_trivially_copy_constructible<C>::value
<< endl;
return 0;
}
|
Output:
is_trivially_copy_constructible:
int: true
A: true
B: false
C: false
Program 2:
#include <iostream>
#include <type_traits>
using namespace std;
struct Ex1 {
string str;
};
struct Ex2 {
int n;
Ex2( const Ex2&) = default ;
};
int main()
{
cout << boolalpha;
cout << "Ex1 is copy-constructible? " ;
cout << is_copy_constructible<Ex1>::value
<< endl;
cout << "Ex1 is trivially copy-constructible? " ;
cout << is_trivially_copy_constructible<Ex1>::value
<< endl;
cout << "Ex2 is trivially copy-constructible? " ;
cout << is_trivially_copy_constructible<Ex2>::value
<< endl;
cout << "Ex2 is nothrow copy-constructible? " ;
cout << is_nothrow_copy_constructible<Ex2>::value
<< endl;
}
|
Output:
Ex1 is copy-constructible? true
Ex1 is trivially copy-constructible? false
Ex2 is trivially copy-constructible? true
Ex2 is nothrow copy-constructible? true
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