Question

I have another problem I can’t seem to solve…, or find on this site…

I have an object (called DataObject) with a map, declared as follows:

std::map<size_t, DataElement*> dataElements;

Now i have a copy function (used in the copy constructor):

void DataObject::copy(DataObject const &other) {

    //here some code to clean up the old data in this object...

    //copy all the elements:
    size = other.getSize();
    for(size_t i = 0; i < size; ++i) {
            DataElement* dat = new DataElement(*other.dataElements[i]);
            dataElements[i] = dat;
    }

}

This doesn’t compile, since dataElements[i] is not possible on a const object. How do I make a deep copy of all the elements in the map that is owned by a const object?

I know that the find() function is possible on a const map, but then how do I get to the actual object that I want to copy?

Answer 1

std::map<size_t, DataElement*>::const_iterator it = other.dataElements.begin();
while(it != other.dataElements.end())
{
    dataElements[it->first] = new DataElement(*(it->second));
    ++it;
}

I’m almost positive this should work.