📌  相关文章
📜  C++中带有示例的std :: is_trivially_move_constructible

📅  最后修改于: 2021-05-30 02:41:42             🧑  作者: Mango

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是琐碎的可构造类型,则返回布尔值true,否则返回false。

头文件:

#include

模板类别:

template< class T >
struct is_trivially_move_constructible;

句法:

std::is_trivially_move_constructible::value

参数:模板std :: is_trivially_move_constructible接受单个参数T(Trait class)来检查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:

  • 正确:如果类型T是可平移的可构造对象。
  • 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 
#include 
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::value
         << endl;
  
    // Check if class A is trivially
    // move constructible or not
    cout << "class A: "
         << is_trivially_move_constructible::value
         << endl;
  
    // Check if class B is trivially
    // move constructible or not
    cout << "class B: "
         << is_trivially_move_constructible::value
         << endl;
  
    // Check if enum class C is trivially
    // move constructible or not
    cout << "enum class C: "
         << is_trivially_move_constructible::value
         << endl;
  
    // Check if class D is trivially
    // move constructible or not
    std::cout << "class D: "
              << is_trivially_move_constructible::value
              << endl;
    return 0;
}
输出:
int: true
class A: true
class B: true
enum class C: true
class D: true

程式2:

// C++ program to demonstrate
// std::is_trivially_move_constructible
#include 
#include 
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::value
         << '\n';
  
    // Check if struct Ex1 is trivially
    // move constructible or not
    cout << "Ex1 is trivially move-constructible? "
         << is_trivially_move_constructible::value
         << '\n';
  
    // Check if struct Ex2 is trivially
    // move constructible or not
    cout << "Ex2 is trivially move-constructible? "
         << is_trivially_move_constructible::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/

要从最佳影片策划和实践问题去学习,检查了C++基础课程为基础,以先进的C++和C++ STL课程基础加上STL。要完成从学习语言到DS Algo等的更多准备工作,请参阅“完整面试准备课程”