why not crash after the temporary object is destroyed

Question

class C
{
public:
    int True(int i) const
    {
        return i+2;
    }
};


const C& F(const C& c)
{
    return c;
}

int main()
{ 
    const C& c =         


        

Answer 1

This invokes undefined behaviour. As soon as the full expression involving F(C()) completes, the temporary created by C() is destroyed, so the reference returned by F is no longer valid.

However, undefined behaviour does not guarantee your program will crash. In more annoying cases (like this) it simply causes subtle, hard to diagnose bugs. As for why this undefined behaviour gives you this specific result, I refer you to this famous answer.