Question

I have the following functions (wrote in Visual C++ 2005)

int &getInt_1()
{
    int a = 5;
    int &p = a;
    int p1 = p; // Line 1
    return p1;
}

int &getInt_2()
{
    int a = 5;
    int &p = a;
    return p;
}

As I have known so far, both the above functions return address of local variable. If I am right, then I have some questions as follows:

1. What are the differences between above functions? Why getInt_1() gets warning from the compiler ("returning address of local variable") while getInt_2() does not?

2. What does Line 1 mean? After Line 1, does p1 become a reference to a as well?

Answer 1

1. getInt_1 returns a reference to p1. getInt_2 returns a reference to a. Both are the same undefined behavior, don’t do it. VC should give a warning on both.
2. No, you just copy the value.