friend cannot access private variables?

Question

class LongInt
{

    friend ostream & operator <<(ostream & os, const LongInt & integer);

...
}

ostream & operator <<(ostream & os, LontInt & container)
{
    os << container.number.size(); //error here


    return os;
}

error: 'std::vector LongInt::number' is private vector number; ^

I don't understand why I can't access the variable, does it have to do something with the fact that the member variable is a vector?

-1 **not the real code** (given code has syntax errors and mis-spelings) — Cheers and hth. - Alf, Feb 28 '14 at 04:27

score 3 · Accepted Answer · answered Feb 28 '14 at 04:16

3

Because it's not a friend of that function: the signature is different. Note const modifier of the second parameter.

answered Feb 28 '14 at 04:16

Denis Itskovich

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ah, weird, it should have given me a different error msg. – OnTheFly Feb 28 '14 at 04:17
@OnTheFly No, it shouldn't. This because `friend` specifier does not obligate you to have function with specified signature. If you are trying to use private members in outer class/global function it will check whether this class/global function is in the friend list. – Denis Itskovich Feb 28 '14 at 04:19

score 1 · Answer 2 · answered Feb 28 '14 at 04:15

1

I think you are missing a const in the declaration before LongInt, which makes the signatures different, and the compiler doesn't think it's the same function that you declared as friend.

answered Feb 28 '14 at 04:15

DS.

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friend cannot access private variables?

2 Answers2