copy initialization

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[编辑] 语法

[编辑] 解释

• 如果T是一个类类型，该类型的other的简历不合格版本的T或一类来自T，T的构造研究和选择最佳匹配的重载决议。然后调用该构造函数初始化对象.

  Original:

  If T is a class type and the type of other is cv-unqualified version of T or a class derived from T, the constructors of T are examined and the best match is selected by overload resolution. The constructor is then called to initialize the object.

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• 如果T是一个类类型，和类型的other是不同的，或如果T非类的类型，但类型other是一个类的类型，它可以转换从类型用户定义的转换序列otherT检查和最佳的一种是通过重载决议。转换的结果，这是一个临时目标类型的prvalue，然后使用直接初始化对象。最后一步是淘汰和结果的转换功能直接构建在目标对象的内存分配，但需要拷贝构造函数可以访问，即使它不使用.

  Original:

  If T is a class type, and the type of other is different, or if T is non-class type, but the type of other is a class type, 用户定义的转换序列 that can convert from the type of other to T are examined and the best one is selected through overload resolution. The result of the conversion, which is a prvalue temporary of the destination type, is then used to 直接初始化 the object. The last step is usually 淘汰 and the result of the conversion function is constructed directly in the memory allocated for the target object, but the copy constructor is required to be accessible even though it's not used.

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• 否则（如果没有T也不other的类型是类类型），标准的转换中使用，如果必要的话，other的cv不合格版本的T的值转换.

  Original:

  Otherwise (if neither T nor the type of other are class types), 标准的转换 are used, if necessary, to convert the value of other to the cv-unqualified version of T.

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[编辑] 注释

[编辑] 为例

#include <string>
#include <utility>
#include <memory>
 
int main()
{
    std::string s = "test"; // OK: constructor is non-explicit
    std::string s2 = std::move(s); // this copy-initialization performs a move
 
//  std::unique_ptr<int> p = new int(1); // error: constructor is explicit
    std::unique_ptr<int> p(new int(1)); // OK: direct-initialization
 
    int n = 3.14;    // floating-integral conversion
    const int b = n; // const doesn't matter
    int c = b;       // ...either way
}

[编辑] 另请参阅

• 默认的初始化
• 直接初始化
• 集合初始化
• 表初始化