overloading ++ --

[mickey]

hello,
refering to my post #10, could you show me any examples of operations (assigment or other) for which at first the returned value of operator+= has to be 'const' and at second, examples for which returned value of operator+= mustn't be 'const' ?
(my problem is 'const' on returned value....)
Thanks.

[jacek]

could you show me any examples of operations (assigment or other) for which at first the returned value of operator+= has to be 'const' and at second, examples for which returned value of operator+= mustn't be 'const' ?

There are no "must" or "musn't" in this case, but you don't gain anything if you return const reference instead of plain reference.

[wysota]

I can't think of any situation where the return value of operator+= would have to return a const object. You can do that of course but I just don't see a point.

X x;
x+=7; // OK
x = ++(x+=7); // invalid for const & operator+=

X x;
x+=7; // OK
x = ++(x+=7); // invalid for const & operator+=

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The last line would be invalid if operator+= returned a const object.