Question

I have a member function like

setResult(const std::string &s)
{
         this->m_result = s;
}

After checking, I found this->m_result‘s address is the same as s. Will m_result disappear (or become garbage) when s goes out of scope if s is a stack object?

Answer 1

Probably not; if m_result is a std::string, it will deep-copy the data contents.

Anyway, in places like assignment operators, you’d normally check against this kind of self-assignment. The idiom is:

obj& operator=(const obj& o) {
    if ( this != &o ) // ...
}

The same goes for your case, where you could potentially check it &m_result is different from the passed in string. But std::string are usually implemented so that self-copying is OK.