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Returning by reference a member of a destroyed local variable


Returning by reference a member of a destroyed local variable

By : FatalError
Date : November 22 2020, 10:33 AM
To fix this issue Since foo returns its return value by value (not by reference), foo makes a copy of the vector to return. It copies from the reference it got back from getNumbers as part of the return before it destroys the local variable a, so at the time it makes the copy, the reference is still valid.
So this code is fine.
code :


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C++: Returning a member variable by reference in member function

C++: Returning a member variable by reference in member function


By : Max Raj
Date : March 29 2020, 07:55 AM
With these it helps You are making a copy.
The function get does indeed return a reference, but you are assigning it by-value:
code :
HeavyClass foo = HeavyClass::get(); // critical line
const HeavyClass& foo = HeavyClass::get()
Returning a reference local variable assigned by reference

Returning a reference local variable assigned by reference


By : Prince Samuel
Date : March 29 2020, 07:55 AM
it should still fix some issue You aren't returning a reference to a local variable. The following code returns a reference to a local variable:
code :
 O& foo() {
     O o;
     return o;
 }
struct O {};
static O s_o;

O& foo() { return s_o; } // returns a reference, to s_o

O& bar() {
    O& o = foo(); // os now refers to s_o;
    return o; // o is a reference, but it refers to s_o,
    // so this returns a reference to s_o, not o.
    // we're returning "O&", not "(O&)&".
}
O* bar(); // returns a pointer to X.
O* optr = bar(); // optr points to X.
return optr; // returns the address of x.
O& foo() {
    return bar();
}
avoid returning local references (reference to local variable returned - warning)

avoid returning local references (reference to local variable returned - warning)


By : user15563
Date : March 29 2020, 07:55 AM
help you fix your problem Unless there is a valid reason not to, prefer to return an object over a pointer allocated on heap.
Advantages of returning an object
Is returning by reference of a member variable EVER acceptable?

Is returning by reference of a member variable EVER acceptable?


By : Peter
Date : March 29 2020, 07:55 AM
To fix the issue you can do It's perfectly fine to return a reference to something that will outlive the function call. When you return an lvalue reference to a class data member, just make sure the class instance is itself an lvalue:
code :
struct Foo
{
    X data;

    X & the_data() &   { return data; }
//                ^^^
    X && the_data() && { return std::move(data); }
};
difference between view reference to member variable and local variable

difference between view reference to member variable and local variable


By : aprilherbertlovely
Date : March 29 2020, 07:55 AM
Any of those help You should always use the minimal scope. So when you declare a variable you should ask yourself:
"Will I need this variable later in a different function?"
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