return reference or not

[Viet Le Hong]

Should I return reference to a temporaty object in a function. I think I
should but g++ 3.2 always warns this thing.

Eg
..
A& test(A &a, A &aa)
{
A res;
.........
.... doing some thing....

return res;
}


Viet

 

[Jakob Bieling]

Should I return reference to a temporaty object in a function. I think I
should but g++ 3.2 always warns this thing.

Why do you think you should?

Eg
.
A& test(A &a, A &aa)
{
A res;
.........
.... doing some thing....

return res;

Here the object 'res' will be destroyed, so the reference is invalid.
That is why it is not allowed. And yes, g++ 3.2 is right.

}

hth

 

[WW]

Why do you think you should?


Here the object 'res' will be destroyed, so the reference is
invalid. That is why it is not allowed. And yes, g++ 3.2 is right.

Calrification: Actually it is allowed, "only" results in undefined behavior.
g++ is very nice and warns about things like this but not all:

char const *getC() {
std::string x;
// add something to x
return x.c_str();
}

Same thing in another form, but g++ has already no way to detect this.

 

[WW]

Calrification

Khm. Clarification it is.

 

[jeffc]

Should I return reference to a temporaty object in a function. I think I
should ...

What makes you think you "should"?

 

[Niklas Borson]

What makes you think you "should"?

Should a reference outlive the object it refers to?

The answer to your question is the same as the answer to the
above question.