不能声明具有一个参数的匿名对象 [英] Anonymous object with one argument cannot be declared

问题描述

有这个代码：

class SomeClass
{
public:
    SomeClass(){}

    SomeClass(SomeClass& b){}

    SomeClass(SomeClass&b, SomeClass& c){}
};

int main()
{
    SomeClass a;
    SomeClass(); // works all right
    //SomeClass(a); error: redeclaration of ‘SomeClass a’
    SomeClass(a, a); // works all right
    return 0;
}

可以声明SomeClass的具有0和2个参数的匿名对象，只用一个参数声明。我假设写入

Anonymous object of SomeClass with 0 and 2 parameters can be declared, however it cannot be declared with only 1 argument. I assume that writing

SomeClass(a);

与

SomeClass a;

如何创建带有一个参数的匿名对象？

How to create anonymous object with one argument?

推荐答案

您可以在自己的语句中构建一个临时对象，例如：

You can construct a temporary object in a statement of its own with something like:

(SomeClass)a;

或

(SomeClass(a));

正如你所观察到的，需要使用括号来解决声明和表达式语句之间的歧义

As you've observed, the parentheses are needed to resolve the ambiguity between a declaration and an expression statement.

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