Why could this C++ program run successfully even without constructing the class object?

Why do this C++ program could run successfully even without constructing the class object? Let's see the code as below: ``` #include<iostream> using namespace std; class Dopey { public: Dopey() {cout << "Dopey\n";} }; class Bashful { public: Bashful() { cout << "BashFul\n";} void f() { cout << " f \n";} int i; }; class Sneezy { public: Sneezy(int i) {cout << "copy int \n";} Sneezy(Bashful d) { cout << "copy Bashful\n";} Sneezy(Bashful* d) {d->f();d->i=100;} //How could this be correct without // constructing d !!!!!!!! Sneezy(); }; class Snow_White { public: Snow_White(); Dopey dopey; Sneezy sneezy; Bashful bashful; private: int mumble; }; Snow_White::Snow_White() : sneezy(&bashful) { mumble = 2048; } int main() { Snow_White s; return 0; } ``` This program could run successfully , the cout are as below: ``` Dopey f BashFul ``` see, `without constructing bashful,the f() could be invoked`, why? and when i change the function `Snow_White::Snow_White()` to the below: ``` Snow_White::Snow_White() : sneezy(bashful) { mumble = 2048; } ``` it also `runs successfully without constructing bashful` , the cout are as below: ``` Dopey copy Bashful Bashful ``` Any interpretation will be appreciated ! THX !