std::is_trivially_move_constructible in C++ with Examples
Last Updated :
12 Jun, 2020
The std::is_trivially_move_constructible template of C++ STL is present in the <type_traits> header file. The std::is_trivially_move_constructible template of C++ STL is used to check whether the T is trivially move constructibe or not. It return the boolean value true if T is trivially move constructible type, Otherwise return false.
Header File:
#include<type_traits>
Template Class:
template< class T >
struct is_trivially_move_constructible;
Syntax:
std::is_trivially_move_constructible<T>::value
Parameter: The template std::is_trivially_move_constructible accepts a single parameter T(Trait class) to check whether T is trivially move constructible type or not.
Return Value: The template std::is_trivially_move_constructible returns a boolean variable as shown below:
- True: If the type T is a trivially move constructible.
- False: If the type T is not a trivially move constructible.
Below is the program to demonstrate std::is_trivially_move_constructible in C++:
Program 1:
#include <iostream>
#include <type_traits>
using namespace std;
class A {
};
class B {
B() {}
};
enum class C : int { x,
y,
z };
class D {
int v1;
double v2;
public :
D( int n)
: v1(n), v2()
{
}
D( int n, double f)
noexcept : v1(n), v2(f) {}
};
int main()
{
cout << boolalpha;
cout << "int: "
<< is_trivially_move_constructible< int >::value
<< endl;
cout << "class A: "
<< is_trivially_move_constructible<A>::value
<< endl;
cout << "class B: "
<< is_trivially_move_constructible<B>::value
<< endl;
cout << "enum class C: "
<< is_trivially_move_constructible<C>::value
<< endl;
std::cout << "class D: "
<< is_trivially_move_constructible<D>::value
<< endl;
return 0;
}
|
Output:
int: true
class A: true
class B: true
enum class C: true
class D: true
Program 2:
#include <iostream>
#include <type_traits>
using namespace std;
struct Ex1 {
Ex1() {}
Ex1(Ex1&&)
{
cout << "Throwing move constructor!" ;
}
Ex1( const Ex1&)
{
cout << "Throwing copy constructor!" ;
}
};
struct Ex2 {
Ex2() {}
Ex2(Ex2&&) noexcept
{
cout << "Non-throwing move constructor!" ;
}
Ex2( const Ex2&) noexcept
{
cout << "Non-throwing copy constructor!" ;
}
};
int main()
{
cout << boolalpha;
cout << "Ex1 is move-constructible? "
<< is_move_constructible<Ex1>::value
<< '\n' ;
cout << "Ex1 is trivially move-constructible? "
<< is_trivially_move_constructible<Ex1>::value
<< '\n' ;
cout << "Ex2 is trivially move-constructible? "
<< is_trivially_move_constructible<Ex2>::value
<< '\n' ;
}
|
Output:
Ex1 is move-constructible? true
Ex1 is trivially move-constructible? false
Ex2 is trivially move-constructible? false
Reference: http://www.cplusplus.com/reference/type_traits/is_trivially_move_constructible/
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