CODEWITHSUNDEEP
c++
birgersp
birgersp

Reputation: 4956

Why is the = operator deleted, and how can I work around it?

I'm trying to set one of the elements of an array to be a different object. But, the compiler is deleting the = operator. Why is it doing that here, exactly? And how can I work around it?

Example code:

struct IntContainer
{

    IntContainer(const int value) :
    value(value)
    {
    }

    IntContainer() :
    IntContainer(0)
    {
    }

    const int value;
};

int main(int argc, char** argv)
{

    IntContainer intContainers[3];
    IntContainer newIntContainer(420);
    intContainers[0] = newIntContainer; // <-- Causes compiler error

    return 0;
}

The compiler error I'm getting when compiling this snippet is:

main.cpp: In function 'int main(int, char**)':
main.cpp:23:24: error: use of deleted function 'IntContainer& IntContainer::operator=(const IntContainer&)'
     intContainers[0] = newIntContainer; // <-- Causes compiler error:
                        ^~~~~~~~~~~~~~~
main.cpp:2:8: note: 'IntContainer& IntContainer::operator=(const IntContainer&)' is implicitly deleted because the default definition would be ill-formed:
 struct IntContainer
        ^~~~~~~~~~~~
main.cpp:2:8: error: non-static const member 'const int IntContainer::value', can't use default assignment operator

Upvotes: 0

Views: 2069

Answers (1)

user123
user123

Reputation: 9071

The compiler generally gives you operator= and the copy constructor for free, but when a class contains a const member, it makes no sense to generate operator= because you can't perform an assignment to the const member.

You could write your own, but you still wouldn't be able to assign values to the const member.

Upvotes: 10

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