Re: How to create a class that casting to int explicitly only?

From:
Tao Wang <Dancefire@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Wed, 30 Jul 2008 04:34:50 -0700 (PDT)
Message-ID:
<14b592aa-b927-4340-b219-70eef0c8549f@k36g2000pri.googlegroups.com>
On Jul 30, 7:28 pm, Nick Keighley <nick_keighley_nos...@hotmail.com>
wrote:

On 30 Jul, 10:18, Tao Wang <Dancef...@gmail.com> wrote:

Hi,

I have a class Data as following

class Data{
...

};

I know if I want to cast it to int implicitly I should write like
following:

class Data{
...
public:
   operator int() {...};

};

So, I can use the class like,

Data d(1234);
int a = d;

However, what I really want is that user of class Data have explicitly
cast it to int.

that is, user should write the code like:

int a = (int) d;

other than:

int a = d;

How can I make the cast to int explicitly only?


does this do what you want?

class Data
{
    public:
        explicit Data(int);

};

--
Nick Keighley


No, it is in wrong direction.

What I expected result is

Data d(1234);

int a = d; // error
int a = (int) d; // OK

Your solution is provide explicitly casting FROM int, rather than to
int.

How this be done?

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