dynamic cast for references

Question

I use dynamic cast for safety:

here is the code I use with pointers:

XYZ xyz = dynamic_cast<XYZ*>(abc);
if (xyz == nullptr)
{
    // TODO handle error
}

Now is there a way to do the same but with references:

XYZ& xyz = dynamic_cast<XYZ&>(abc);
if (xyz == nullptr)
{
    // TODO handle error
}

this code doesn't compile but I am asking is there a way to do that in a similar fashion.

Baum mit Augen · Accepted Answer · 2014-06-09T17:27:32.200

6

dynamic_cast throws an exception on failure if used with references. To handle failure, catch the exception:

try {
    XYZ& xyz = dynamic_cast<XYZ&>(abc);
}
catch (std::bad_cast& e) {
    //handle error
}

edited Jun 09 '14 at 17:27

answered Jun 09 '14 at 17:12

Baum mit Augen

49,044
25
144
182

score 3 · Answer 2 · answered Jun 09 '14 at 17:11

3

Yes, but since you're casting to a reference, nullptr is not a possible outcome. Instead, if the dynamic type of abc is not convertible to XYZ, the cast will throw std::bad_cast.

answered Jun 09 '14 at 17:11

dlf

9,045
4
32
58

so that mean that in cast of pointers a nullptr is returned while in case of references an exception is thrown? – mmohab Jun 09 '14 at 17:14
Yes, that is correct. – dlf Jun 09 '14 at 17:14

dynamic cast for references

2 Answers2