[C++] Method return a reference type

class A {
public:
    string& getStr() {
        return m_Str;
    }
    string m_Str;
};

int main() {
    // Create a A object
    A *a = new A();
    a->m_Str = "abc";

    // Get m_Str
    string& s = a->getStr();
    string s2 = a->getStr();

    // Check the address
    printf("%p\n%p\n%p\n", &s, &s2, &a->m_Str);

    // Try to change something of m_Str
    s[1] = 'd';
    cout << a->getStr() << endl;

    // Clear
    delete a;
    return 0;
}

Output:

0x7fa613c03450
0x7fff5e4a74d0
0x7fa613c03450
adc

Conclusion:

If you return a reference type from a method and you do not use a reference type to get the return value of this method. This will have a copy occurred.