<type_traits>头文件中提供了C++ STL的std::is_trivially_move_constructible模板。 C++ STL的std::is_trivially_move_constructible模板用于检查T是否平移构造体。如果T是平凡的可构造类型,则它返回布尔值true,否则返回false。
头文件:
#include<type_traits>
模板类别:
template< class T > struct is_trivially_move_constructible;
用法:
std::is_trivially_move_constructible<T>::value
参数:模板std::is_trivially_move_constructible接受单个参数T(Trait类),以检查T是否是平凡的可构造类型。
返回值:模板std::is_trivially_move_constructible返回一个布尔变量,如下所示:
- True:如果类型T是平凡的可构造的。
- False:如果类型T不是平凡的可构造对象。
下面是演示C++中std::is_trivially_move_constructible的程序:
程序1:
// C++ program to demonstrate
// std::is_trivially_move_constructible
#include <iostream>
#include <type_traits>
using namespace std;
// Declaration of classes
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;
// Check if int is trivially
// move constructible or not
cout << "int:"
<< is_trivially_move_constructible<int>::value
<< endl;
// Check if class A is trivially
// move constructible or not
cout << "class A:"
<< is_trivially_move_constructible<A>::value
<< endl;
// Check if class B is trivially
// move constructible or not
cout << "class B:"
<< is_trivially_move_constructible<B>::value
<< endl;
// Check if enum class C is trivially
// move constructible or not
cout << "enum class C:"
<< is_trivially_move_constructible<C>::value
<< endl;
// Check if class D is trivially
// move constructible or not
std::cout << "class D:"
<< is_trivially_move_constructible<D>::value
<< endl;
return 0;
}
输出:
int:true class A:true class B:true enum class C:true class D:true
程序2:
// C++ program to demonstrate
// std::is_trivially_move_constructible
#include <iostream>
#include <type_traits>
using namespace std;
// Declare structures
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!";
}
};
// Driver Code
int main()
{
cout << boolalpha;
// Check if struct Ex1 is move
// constructible or not
cout << "Ex1 is move-constructible? "
<< is_move_constructible<Ex1>::value
<< '\n';
// Check if struct Ex1 is trivially
// move constructible or not
cout << "Ex1 is trivially move-constructible? "
<< is_trivially_move_constructible<Ex1>::value
<< '\n';
// Check if struct Ex2 is trivially
// move constructible or not
cout << "Ex2 is trivially move-constructible? "
<< is_trivially_move_constructible<Ex2>::value
<< '\n';
}
输出:
Ex1 is move-constructible? true Ex1 is trivially move-constructible? false Ex2 is trivially move-constructible? false
参考: http://www.cplusplus.com/reference/type_traits/is_trivially_move_constructible/
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注:本文由纯净天空筛选整理自bansal_rtk_大神的英文原创作品 std::is_trivially_move_constructible in C++ with Examples。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。