Question

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Returning reference to a local variable

I happened to find this code return 5. It’s OK to write it this way or should definitely be avoid?

   int& f() {

     int i = 5; 
     return i;
}

int main(){

    cout<<f()<<endl;    
}

Answer 1

If it works, it works only by accident. This is undefined behavior and should definitely be avoided.

The moment that f returns, there are no longer any guarantees as to what happens to the memory where i lived and what happens when you try to access it.