English 中文(简体)
投放的经营者能否明确?
原标题:Can a cast operator be explicit?

在建筑商方面,加上关键词explicit,当节目设计者没有初衷时,便无法生成物体。 这种机制是否也可供投放者使用?

struct Foo
{
    operator std::string() const;
};

比如,在这里,我希望能够加入<代码>。 Foo into a std:string,但我不想暗中发生这种 cast。

最佳回答

是的,无。

这取决于C++的哪一种版本,你重新使用。

  • C++98 and C++03 do not support explicit type conversion operators
  • But C++11 does.

struct A
{
    //implicit conversion to int
    operator int() { return 100; }

    //explicit conversion to std::string
    explicit operator std::string() { return "explicit"; } 
};

int main() 
{
   A a;
   int i = a;  //ok - implicit conversion 
   std::string s = a; //error - requires explicit conversion 
}

随附<代码>g++-std=c++0x,将出现这一错误:

赞成:13:20

Online demo :

But as soon as you write:

std::string s = static_cast<std::string>(a); //ok - explicit conversion 

The error goes away : http://ideone.com/LhuFd

BTW在C++11中,如果将直线转换为Boolean,则明确转换操作者称为“正文转换操作者”。 此外,如果你想更多地了解暗含和明确的转变,就读到这个专题:

问题回答

暂无回答




相关问题
Undefined reference

I m getting this linker error. I know a way around it, but it s bugging me because another part of the project s linking fine and it s designed almost identically. First, I have namespace LCD. Then I ...

C++ Equivalent of Tidy

Is there an equivalent to tidy for HTML code for C++? I have searched on the internet, but I find nothing but C++ wrappers for tidy, etc... I think the keyword tidy is what has me hung up. I am ...

Template Classes in C++ ... a required skill set?

I m new to C++ and am wondering how much time I should invest in learning how to implement template classes. Are they widely used in industry, or is this something I should move through quickly?

Print possible strings created from a Number

Given a 10 digit Telephone Number, we have to print all possible strings created from that. The mapping of the numbers is the one as exactly on a phone s keypad. i.e. for 1,0-> No Letter for 2->...

typedef ing STL wstring

Why is it when i do the following i get errors when relating to with wchar_t? namespace Foo { typedef std::wstring String; } Now i declare all my strings as Foo::String through out the program, ...

C# Marshal / Pinvoke CBitmap?

I cannot figure out how to marshal a C++ CBitmap to a C# Bitmap or Image class. My import looks like this: [DllImport(@"test.dll", CharSet = CharSet.Unicode)] public static extern IntPtr ...

Window iconification status via Xlib

Is it possible to check with the means of pure X11/Xlib only whether the given window is iconified/minimized, and, if it is, how?