<type_traits>

类模板
<type_traits>

std::is_copy_constructible

template <class T> struct is_copy_constructible;
is copy constructible

用于识别Tis a copy constructible type.

A copy constructible type is a type that can be constructed from a value or reference of the same type. This includes scalar types and copy constructible classes.

A copy constructible class is a class that has a copy constructor (either its implicit constructor or a custom defined one).

要放回的字符的is_copy_constructible类继承自integral_constant,其值为true_typefalse_type,取决于Tis copy constructible.

模板参数

T
一个完整类型,或者void(可能带 cv 限定),或者一个未知边界的数组。

成员类型

Inherited from integral_constant
成员类型定义
value_typebool
类型true_type 或 false_type

成员常量

Inherited from integral_constant
成员常量定义
trueorfalse

成员函数

Inherited from integral_constant

示例

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// is_copy_constructible example
#include <iostream>
#include <type_traits>

struct A { };
struct B { B(B&&){} };
struct C { C(const C&){} };

int main() {
  std::cout << std::boolalpha;
  std::cout << "is_copy_constructible:" << std::endl;
  std::cout << "int: " << std::is_copy_constructible<int>::value << std::endl;
  std::cout << "A: " << std::is_copy_constructible<A>::value << std::endl;
  std::cout << "B: " << std::is_copy_constructible<B>::value << std::endl;
  std::cout << "C: " << std::is_copy_constructible<C>::value << std::endl;
  return 0;
}

输出
is_copy_constructible:
int: true
A: true
B: false
C: true


另见