which operator overloading has been used for ifstream object to evalute to boolean

Question

I am new to C++. recently I come across the following code

ifstream in("somefile");

if(in){
    //read the file....
}

I am wondering which operator overloading the ifstream might have used for the in object to automatically evaluate to boolean in if condition. I tried but couldnt find a clue. please help me. thank in advance

Answer 1

It's actually operator void *.

It's overridden to return a non-zero pointer if the stream is valid, and a NULL pointer otherwise. The pointer it returns is meaningless and should not be dereferenced, it's only there to be evaluated in a boolean context.