Why this operator returns warning?

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Why this operator++ return a warning?

C++

Human& Human::operator++(int){
    Human temp(*this);
    operator++();
    return temp;    // warning here.
}

The warning is:
Reference to stack memory associated with local variable 'temp' returned.

There was no problem with the result except for the warning though.
What is the proper way to do it?
I'm learning about overloading.
I'm using XCode 7.1.1

another pair of the increment works without warning.

C++

Human& Human::operator++(){
    _health++ ;
    _attack++ ;
	_defense++;
    return *this;
}

Posted 8-Dec-15 0:13am

Are Riff

Updated 8-Dec-15 0:22am

v2

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Jochen Arndt · Accepted Answer · 2015-12-08T00:25:00

The local variable temp goes out of scope when the function returns and is no longer valid afterwards.

So you should return a value here rather a reference:

Human Human::operator++(int){
    Human temp(*this);
    operator++();
    return temp;
}

[EDIT]
See also here http://en.cppreference.com/w/cpp/language/operator_incdec[^] the Notes below the table:

Quote:
Prefix versions of the built-in operators return references and postfix versions return values

I suggest also to bookmark the above website en.cppreference.com (or a similar one) in your browser. It will be really helpful while trying out C++ features.